Special Science Teleclass: Solar Astronomy

Saturday March 25, 2017

This is a recording of a recent live class I did with an entire high school astronomy class. I’ve included it here so you can participate and learn, too!


Light is energy that can travel through space. How much energy light has determines what kind of wave it is. It can be visible light, x-ray, radio, microwave, gamma or ultraviolet. The electromagnetic spectrum shows the different energies of light and how the energy relates to different frequencies, and that’s exactly what we’re going to cover in class. We’re going to talk about light, what it is, how it moves, and it’s generated, and learn how astronomers study the differences in light to tell a star’s atmosphere from  millions of miles away.


I usually give this presentation at sunset during my live workshops, so I inserted slides along with my talk so you could see the pictures better. This video below is long, so I highly recommend doing this with friends and a big bowl of popcorn. Ready?


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Materials:


  • Hair (one strand)
  • Tape
  • Pencil
  • Ruler or yardstick
  • Paper
  • Calculator
  • Red laser
  • Flashlight
  • Glass of water
  • Large chocolate bar
  • Microwave
  • Plate
  • Orange highlighter
  • Diffraction grating OR use an old CD
  • Print out this worksheet to fill in as we go along!


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Special Science Teleclass: Black Holes

Monday September 29, 2014

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!


We’re ready to deal with the topic you’ve all been waiting for! Join me as we find out what happens to stars that wander too close, how black holes collide, how we can detect super-massive black holes in the centers of galaxies, and wrestle with question: what’s down there, inside a black hole?


Materials:


  • marble
  • metal ball (like a ball bearing) or a magnetic marble
  • strong magnet
  • small bouncy ball
  • tennis ball and/or basketball
  • two balloons
  • bowl
  • 10 pennies
  • saran wrap (or cup open a plastic shopping bag so it lays flat)
  • aluminum foil (you’ll need to wrap inflated balloons with the foil, so make sure you have plenty of foil)
  • scissors

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Key Concepts

What’s a black hole made of? Black holes are make of nothing but space and time, and they are the strangest things in nature.  It’s BLACK because does not emit or reflect light.  Black holes are the darkest black in the universe – no matter how powerful of a light you shine on it, even if it’s a million watt flashlight, no light ever bounces back, because its truly a ‘hole’ in space.


And a HOLE means nothing entering can escape. Anything that crosses the edge is swallowed forever. Scientists think of black holes as the edge of space, like a one-way exit door.


Biggest myth about black holes: Black holes are not vacuum cleaners with infinite sized bags. They do not roam around the universe sucking up everything they can find. They will grow gradually as stars and matter falls into them, but they do not seek out prey like predators. It just sits there with its mouth open, waiting for dinner.


Here’s an example of what a black hole is: If you take a ball and toss it up in the air, does it come back down to you? Sure! Toss it up even higher now… and it still comes back, right? What if you toss it up so fast that it exceeds the escape velocity of earth? (7 miles per second) Will it ever come back? No. The escape velocity depends on the gravitational pull of an object. The escape velocity of the sun is 400 miles per second. A black hole is an object that has an escape velocity greater than the speed of light. That’s exactly what a black hole is.


So, a black hole is a region where gravity is so strong that any light that tries to escape gets dragged back.  Because nothing can travel faster than light, everything else gets dragged back too!


Another interesting fact about black holes is that they are a place where gravity is so intense that time stops. This means that an object that falls into a black hole will never reappear, because they are frozen in time.


I often hear the question – how big are black holes? There’s no limit to the size of a black hole – it can be as large or as small as you can imagine it to be (and then some!). The more massive a black hole is, the more space it will take up, and the larger the radius of the event horizon. One of the largest and heaviest black holes is actually the super massive black hole at the center of our own Milky Way galaxy, about 30,000 light years away. Don’t worry, since it’s so far away and it’s not actively feeding.


Black holes are believed to be able to evaporate. Steven Hawking suggested that black holes aren’t exactly all black, but they emit a tiny bit of radiation, which comes directly from the black hole’s mass. This means as the black hole emits radiation, it loses mass, and shrinks.


If you’re looking for black holes, the nearest one is called V4641 Sgr and it’s 1,600 light years away in the Sagittarius arm of the Milky Way.  This is actually a rare type of black hole called a micro quasar. Click here for a downloadable Map of Black Holes.


One of the biggest misconceptions about black holes is that they are thought to be giant vacuum cleaners with infinitely large bags. Actually, they don’t go around vacuuming up all the matter they find. (If they did, they would eventually inhale all the matter in the universe and there’s be nothing left but black holes.) In fact, black holes can’t suck up all the matter because each black hole has its very own event horizon, which means that matter has to first cross that horizon in order to be eaten by the black hole. If it doesn’t go past that horizon, then it will not be sucked into the black hole.


Still crazy for black holes? Download the Exploring Black Holes PDF poster file and also try playing the Black Hole Space Travel game, which was developed by a team of NASA scientists. Enjoy!


Questions to Ask

  1. What are three different ways to detect a black hole?
  2. How many ways can a black hole kill you? Can you name them?
  3. What happens if you get close to a black hole, but not close enough to get sucked in? (Remember your magnet-marble experiment!)
  4. What if you watch someone get sucked in? What does it look like?
  5. What’s the most interesting thing you learned from the video about black holes?
  6. Why does a supernova explode? (Remember your two-ball experiment?)
  7. What causes a black hole to form?
  8. Does a black hole search for its next victim?
  9. Where is the closest super-massive black hole?
  10. What is gravitational lensing and why does it work? (Remember your marble-bowl experiment!)

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Special Science Teleclass: Astronomy

Monday September 22, 2014

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I've included it here so you can participate and learn, too

Our solar system includes rocky terrestrial planets (Mercury, Venus, Earth, and Mars), gas giants (Jupiter and Saturn), ice giants (Uranus and Neptune), and assorted chunks of ice and dust that make up various comets and asteroids.

Did you know you can take an intergalactic star tour without leaving your seat? To get you started on your astronomy adventure, I have a front-row seat for you in a planetarium-style star show. I usually give this presentation at sunset during my live workshops, so I inserted slides along with my talk so you could see the pictures better. This video below is long, so I highly recommend doing this with friends and a big bowl of popcorn. Ready?

[am4show have='p8;p9;p11;p38;p96;' guest_error='Guest error message' user_error='User error message' ] Materials:

    • Two balls, one larger than the other (like a soccer and a tennis ball, or bouncy ball and tennis ball)
    • Print out this worksheet to fill in as we go along!

 

Download the Black Hole Explorer Game. This was created by a team of scientists, you can use this set of instructions to build your own black hole board game. It plays two different ways: competitively and cooperatively. Black Hole Explorer was created for NASA by the Harvard-Smithsonian Center for Astrophysics.

This is a PDF download, so you'll need Adobe Acrobat Reader to view the file. It's fun, easy, and totally free for your family and students to enjoy!

Key Concepts

The solar system is the place that is affected by the gravity our sun. Our solar system includes rocky terrestrial planets (Mercury, Venus, Earth, and Mars), gas giants (Jupiter and Saturn), ice giants (Uranus and Neptune), and assorted chunks of ice and dust that make up various comets and asteroids. The eight planets follow a near-circular orbit around the sun, and many have moons.

Two planets (Ceres and Pluto) have been reclassified after astronomers found out more information about their neighbors. Ceres is now an asteroid in the Asteroid Belt between Mars and Jupiter. Beyond Neptune, the Kuiper Belt holds the chunks of ice and dust, like comets and asteroids as well as larger objects like dwarf planets Eris and Pluto.

Beyond the Kuiper belt is an area called the Oort Cloud, which holds an estimated 1 trillion comets. The Oort Cloud is so far away that it's only loosely held in orbit by our sun, and constantly being pulled gravitationally by passing stars and the Milky Way itself. The Voyager Spacecraft are beyond the heliosphere (the region influenced gravitationally by our sun) but has not reached the Oort Cloud.

Our solar system belongs to the Milky Way galaxy. Galaxies are stars that are pulled and held together by gravity. Globular clusters are massive groups of stars held together by gravity, using housing between tens of thousands to millions of stars. Some galaxies are sparse while others are packed so dense you can't see through them. Galaxies also like to hang out with other galaxies (called galaxy clusters ), but not all galaxies belong to clusters, and not all stars belong to a galaxy.

After a star uses up all its fuel, it can either fizzle or explode. Planetary nebulae are shells of gas and dust feathering away. Neutron stars are formed from stars that go supernova, but aren't big and fat enough to turn into a black hole. Pulsars are spinning neutron stars with their poles aimed our way. Neutron stars with HUGE magnetic fields are known as magnetars. Black holes are the leftovers of a BIG star explosion. There is nothing to keep it from collapsing, so it continues to collapse forever. It becomes so small and dense that the gravitational pull is so great that light itself can't escape.

The sun holds 99% of the mass of our solar system. The sun's equator takes about 25 days to rotate around once, but the poles take 34 days. You may have heard that the sun is a huge ball of burning gas. But the sun is not on fire, like a candle. You can't blow it out or reignite it. So, where does the energy come from?

The nuclear reactions deep in the core transforms 600 million tons per second of hydrogen into helium. This gives off huge amounts of energy which gradually works its way from the 15 million-degree Celsius temperature core to the 15,000 degree Celsius surface.

Active galaxies have very unusual behavior. There are several different types of active galaxies, including radio galaxies (edge-on view of galaxies emitting jets), quasars (3/4 view of the galaxy emitting jets), blazars (aligned so we're looking straight down into the black hole jet), and others. Our own galaxy, the Milky Way, has a super-massive black hole at its center, which is currently quiet and dormant.

Dying stars blow off shells of heated gas that glow in beautiful patterns. William Hershel (1795) coined the term ‘planetary nebula' because the ones he looked at through 18th century telescopes looked like planets. They actually have nothing to do with planets – they are shells of dust feathering away.

When a star uses up its fuel, the way it dies depends on how massive it was to begin with. Smaller stars simply fizzle out into white dwarfs, while larger stars can go supernova. A recent supernova explosion was SN 1987. The light from Supernova 1987A reached the Earth on February 23, 1987 and was close enough to see with a naked eye from the Southern Hemisphere.

Star Gazing

If you haven't attended a "star aprty", you'll want to search for a local Astronomy Club in your aea so you can participate! They are fun, free, and very informative.  In the meantime, here is a series I put together about how to use both telescopes and binoculars to explore the night sky (these were originally done as Facebook Live videos, so when you click the links below, you will be taken directly to my Facebook posts).

Questions to Ask

  1. What's your favorite part about Jupiter?
  2. Which planet is NOW your favorite (after listening to the slide show presentation)?
  3. What happened to the stars in the last slide of the show?
  4. How many moons around Jupiter or Saturn can you see with binoculars?
  5. What's the difference between a galaxy and a black hole?
  6. How many Earths fit inside the sun?

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Magnetic Tornadoes

Sunday September 1, 2013

This lab is a physical model of what happens on Mercury when two magnetic fields collide and form magnetic tornadoes.

You’ll get to investigate what an invisible magnetic tornado looks like when it sweeps across Mercury.

Materials

  • Two clear plastic bottles (2 liter soda bottles work well)
  • Steel washer with a 3/8 inch hole
  • Ruler and stopwatch
  • Glitter or confetti (optional)
  • Duct tape (optional)

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Download Student Worksheet & Exercises

  1. Determine the different water conditions, such as: changing the temperature, changing the volume (height of water), adding another molecule such as oil, isopropyl alcohol, vinegar, and dish soap, adding solid pieces such as glitter, salt, sugar, or small grains. The different mixtures will give different vortex rotation speeds and different drain times. This is equivalent to changing the atmosphere on Earth and seeing how it affects weather (not magnetic) tornadoes. Write the conditions you wish to test in the data table before you start.
  2. Fill one of the soda bottles with water using the data table. Set the bottle upright on the table.
  3. Set the washer on top of the bottle opening. Make sure there’s no cap on the bottle.
  4. Invert the empty bottle over the water‐filled bottle and line up the openings so they can be easily taped together. You want to tape them before they get wet with the washer between them.
  5. Place the two bottles on a table and watch the water drip from the top to the lower bottle as air bubbles move from bottom to top.
  6. Invert so the water is in the top bottle and circle it a couple of times to start a whirlpool in the bottle. You should see a vortex form inside as the top drains into the lower bottle. The hole in the vortex lets the airfrom the lower bottle flow easily into the upper bottle, so the upper drains easily.
  7. When you’ve finished, empty your bottle and add a different solution and repeat the experiment.

What's Going On?

Mercury looks peaceful at first glance. However, when you measure the surface with scientific instruments, you’ll see how the Sun blasts away any hope Mercury has of a thin atmosphere with its radiation and solar wind. Not only that, Mercury is ravaged by invisible magnetic tornadoes that start from the planet’s interior magnetic field. If you’ve ever experienced a tornado, you know how terrifying they can be. Now imagine they are the diameter of your entire planet.

These tornadoes are different from the Earth’s, which form when two weather systems smack into each other, creating instability in the atmosphere. The magnetic tornadoes on Mercury form when two magnetic fields collide. These monstrous cyclones form without warning and disappear within minutes.

Magnetic fields, like the Earth’s, are invisible shields that constantly protect us from the Sun. Our Earth is constantly being bombarded with high energy particles that are deflected off the magnetosphere of our planet. Mercury’s magnetic field is weak and it’s constantly being blasted by solar wind, which also carries a magnetic field. When these two fields collide, the magnetic fields spiral and twist to form a magnetic tornado. (Solar wind is a stream of high energy particles from the Sun’s outer atmosphere.)

Exercises

  1.  Define an atmosphere.
  2. What is a magnetic field?
  3.  Where do magnetic fields come from in planets?
  4. Which planets do not have a magnetic field?

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Sundial

Sunday September 1, 2013

Using the position of the Sun, you can tell what time it us by making one of these sundials. The Sun will cast a shadow onto a surface marked with the hours, and the time-telling gnomon edge will align with the proper time.


In general, sundials are susceptible to different kinds of errors. If the sundial isn’t pointed north, it’s not going to work. If the sundial’s gnomon isn’t perpendicular, it’s going to give errors when you read the time. Latitude and longitude corrections may also need to be made. Some designs need to be aligned with the latitude they reside at (in effect, they need to be tipped toward the Sun at an angle). To correct for longitude, simply shift the sundial to read exactly noon when indicated on your clock. This is especially important for sundials that lie between longitudinal standardized time zones. If daylight savings time is in effect, then the sundial timeline must be shifted to accommodate for this. Most shifts are one hour.


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Download Student Worksheet & Exercises for ALL Sundials


Simple Sundial

  • Index card
  • Scissors
  • Tape


  1. This sundial takes only a couple minutes to make, and reads easily for beginner students.
  2. Cut the template.
  3. Cut your index card into two triangles by cutting from one corner to the opposite diagonal corner. Stack the two triangles and tape together. This is called your gnomon.
  4. Tape the triangle to your 12-hour line, putting tape on both sides of the gnomon as you stick it to the paper.
  5. Put the sundial in a sunny place where it won’t be disturbed (like inside of a sunny window or on a table outdoors).
  6. Point the sundial so that the gnomon is pointing north. This is most easily done if you orient your sundial at exactly noon in your location. Line up the sundial with the Sun so that the shadow the gnomon makes lines up exactly with the 12.
  7. Tape the sundial down so it won’t move or get blown away.
  8. The gnomon must be exactly perpendicular to the hour markers. Use a ruler or a book edge to help you line this up.

Intermediate Sundial

  • 2 yardsticks or metersticks
  • Protractor
  • Chalk
  • Clock


  1. Find a sunny spot that has concrete and grassy area right next to each other. You’re going to poke the yardstick into the grass and draw on the concrete with chalk, so be sure that the concrete goes in an approximately east-west direction.
  2. First thing in the morning, stick one of the yardsticks into the dirt, right at the edge of the concrete.
  3. At the top of the hour (like at 8 a.m. or 9 a.m.), go out to your yardstick to mark a position.
  4. Lay the second yardstick down along the shadow that the upright yardstick makes on the ground. Use chalk to draw the shadow, and use the yardstick to make your line straight.
  5. Label this line with the hour.
  6. Set your timer and run back out at the top of the next hour.
  7. Repeat steps 3-6 until you finish marking your sundial.
  8. When you’ve completed your sundial, fill out the table.

Advanced Sundial

  • Old CD (this can also be the transparent CD at the top of DVD/CD spindles)
  • Empty CD Case
  • Skewer
  • Sticky tape
  • Cardboard or small piece of clay
  • Protractor
  • Scissors
  • Tape
  • Hot glue


This sundial will work for all longitudes, but has a limited range of latitudes. If you live in the far north or far south, you’ll need to get creative about how to mount the CD so that the gnomon is pointed at the correct angle. For example, at the equator, the CD will lie flat (which is easy!), but near the north and south poles, the CD will be upside down.


  1. Cut out the timeline.
  2. Put a line of double-sided sticky tape along the back of the timeline. Extend the tape about ¼” (on the bottom edge) so it’s hanging off a paper a little.
  3. Flip the timeline over and roll the CD along this bottom edge, sticking the timeline to the edge of the CD. The timeline should be facing inward toward the center of the CD, perpendicular to the CD surface.
  4. Now it’s time to plug up the center hole. You can cut out circles from a CD and attach with tape, or use a small piece of clay.
  5. Push the skewer through the exact middle of the CD.
  6. Open up the CD case.
  7. Position the noon marker at the bottom and stick it using a piece of double-sided sticky tape or hot glue.
  8. The other side of the CD is glued to the CD case at the same angle as your latitude. For example, if I live at 43o north, I would use my protractor on the ground along the base of the CD case and lift the CD until the gnomon reads at 43o. Put a dab of hot glue to attach the CD to the lid of the case.
  9. Go outside and point the gnomon north (you may want to use a compass for this if it’s not noon.)
  10. The dial will have a shadow that falls on the timeline. You can read the time right off the timeline.
  11. For advanced students: Timeline correction: Do you remember how the Sun was fast or slow in the Stargazer’s Wall Chart from the lesson entitled: What’s in the Sky? That wavy line is called the Equation of Time, and you’ll need it to correct your sundial if you want to be completely accurate. This is a great demonstration for a Science Fair project, especially when you add a model of the Sun and Earth to help you explain what’s going on.

What’s Going On?

Sundials have been used for centuries to keep track of the Sun. There are different types of sundials. Some use a line of light to indicate what time it is, while others use a shadow.


Here are a couple of different models that, although they look a lot different from each other, actually all work to give the same results! Your sundial will work all days of the year when the Sun is out.


You’ll notice that north is the direction that your shadow’s length is the shortest. However, if you don’t know where east and west are, all you can do is know where north is. The equinox is a special time of year because the Sun rises in the exact east and sets in the exact west, making these two points exactly perpendicular with the north for your location (which they usually aren’t). At sunset, you can view your shadow (quickly before it disappears) and draw it with chalk on the ground, making a line that runs east-west. 90o CCW from the line is north.


In general, sundials are susceptible to different kinds of errors. If the sundial isn’t pointed north, it’s not going to work.  If the sundial’s gnomon isn’t perpendicular, it’s going to give errors when you read the time. Latitude and longitude corrections may also need to be made. Some designs need to be aligned with the latitude they reside at (in effect, they need to be tipped toward the Sun at an angle). To correct for longitude, simply shift the sundial to read exactly noon when indicated on your clock. This is especially important for sundials that lie between longitudinal standardized time zones. The Equation of Time from the advanced lesson entitled: What’s in the Sky? can be used to correct for the Sun running slow or fast. Remember, this effect is due to both the Earth’s orbit not being a perfect circle and the fact that the tilt axis is not perpendicular to the orbit path.  If daylight savings time is in effect, then the sundial timeline must be shifted to accommodate for this. Most shifts are one hour.


Exercises


  1. What kinds of corrections need to be made for your sundial?
  2. When wouldn’t your sundial work?
  3. How can you improve your sundial to be more accurate?

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Atmospheres

Sunday September 1, 2013

Scientists do experiments here on Earth to better understand the physics of distant worlds. We’re going
to simulate the different atmospheres and take data based on the model we use.


Each planet has its own unique atmospheric conditions. Mars and Mercury have very thin atmospheres, while Earth has a decent atmosphere (as least, we like to think so). Venus’s atmosphere is so thick and dense (92 times that of the Earth’s) that it heats up the planet so it’s the hottest rock around. Jupiter and Saturn are so gaseous that it’s hard to tell where the atmosphere ends and the planet starts, so scientists define the layers based on the density and temperature changes of the gases. Uranus and Neptune are called ice giants because of the amounts of ice in their atmospheres.


Materials


  • 4 thermometers
  • 3 jars or water bottles
  • Plastic wrap or clear plastic baggie
  • Wax paper
  • Stopwatch

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>  
Download Student Worksheet & Exercises


  1. Place one thermometer in direct sunlight. This is like the atmosphere of Mercury and Mars.
  2. Place a second thermometer in a jar and cap it. Place this in sunlight. This is the Earth’s, Jupiter’s and Saturn’s atmosphere.
  3. Line the second jar with wax or tissue paper. Place the third thermometer in the jar and cap it. Place it next to the other two in sunlight. This is the atmosphere on Venus.
  4. Insert the fourth thermometer into a plastic baggie, insert it into the bottle and cap it. Make sure the baggie is loose. This is Neptune and Uranus.
  5. Record your data observations in the table, taking data every couple of minutes.

What’s Going On?

Venus is hot enough to melt cannonballs and crush any spaceship that tries to land on the surface. Carbon dioxide is a “greenhouse gas,” meaning that some wavelengths of light can pass through it, but specifically not infrared light, which is also known as heat. Light from the Sun either bounces off the upper cloud layers and back into space, or penetrates the clouds and strikes the surface of Venus, warming up the land. The ground radiates the heat back out, but the carbon dioxide atmosphere is so dense and thick that it traps and keeps the heat down on the surface of the planet. Think of rolling up your windows in your car on a hot day.


The heat is so intense on Venus that the carbon normally locked into rocks sublimated (turned straight from solid to gas) and added to the carbon in the atmosphere, to make even more carbon dioxide.


Mercury doesn’t have much of an atmosphere, which is just like a bare thermometer. There’s nothing to hold onto the heat that strikes the surface. Mars is in a similar situation.


Earth’s atmosphere is simulated by placing the thermometer in a bottle. The Earth has a cloud layer that keeps some of the heat on the planet, but most of it does get radiated back into space. When the clouds are in at night, the planet stays warmer than when it’s clear (and cold).


Venus’s heavy, dense carbon dioxide atmosphere is simulated by using the waxed paper. Venus is the hottest planet in our solar system because of the runaway greenhouse effect that traps most of the heat that makes it through the atmosphere, bouncing it back down to the surface. The average temperature of Venus is over 900oF.


Jupiter and Saturn’s atmospheres are thinner layers of hydrogen and helium than deeper in the core.


Uranus and Neptune are called ice giants because of the amounts of ice in their atmospheres. Their atmospheres are also made of mostly hydrogen and helium.


Exercises


  1. Which atmosphere reached the highest temperature?
  2. Each of the jars received the same amount of energy from the Sun. Why is this not quite like the real solar system?

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Fire & Optics

Sunday September 1, 2013

Today you get to concentrate light, specifically the heat, from the Sun into a very small area. Normally, the sunlight would have filled up the entire area of the lens, but you’re shrinking this down to the size of the dot.


Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes by bending the light. When light passes through a different medium (from air to glass, water, a lens…) it changes speed and usually the angle at which it’s traveling. A prism splits incoming light into a rainbow because the light bends as it moves through the prism. A pair of eyeglasses will bend the light to magnify the image.


Materials


  • Sunlight
  •  Glass jar
  • Nail that fits in the jar
  •   12” thread
  •   Hair from your head
  • 12” string
  • 12” fishing line
  • 12” yarn
  •  Paperclip
  • Magnifying glass
  •  Fire extinguisher
  •  Adult help

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Download Student Worksheet & Exercises


  1. You’re going to concentrate the power of the Sun on a flammable surface.
  2. Please do this on a fireproof surface! This experiment will damage tables, counters, carpets, and floors. Do this experiment on a fireproof surface, like concrete or blacktop.
  3. Hold the magnifier above the leaf and bring it down toward the leaf until you see a bright spot form on its surface. Adjust it until you see the light as bright and as concentrated as possible. First, you’ll notice smoke, then a tiny flame as the leaf burns.
  4. You are concentrating the light, specifically the heat, from the Sun into a very small area. Normally, the sunlight would have filled up the entire area of the lens, but you’re shrinking this down to the size of the dot that’s burning the leaf.
  5. Thermoelectric power plants use this principle to power entire cities by using this principle of concentrating the heat from the Sun.
  6. Never look through anything that has lenses in it at the Sun, including binoculars or telescopes, otherwise what’s happening to the leaf right now is going to happen to your eyeball.
  7. Now for the next part of the lab, do not use water bottles – you want something that doesn’t melt, like a glass jar from the pickles or the mayo.
  8. Remove the lid and punch a hole in the center. Use a drill with a ¼” drill bit or smaller, or a hammer and nail.
  9. Screw the lid on the jar.
  10. Tie one end of the thread to the paperclip.
  11. Poke the other end of the thread inside the hole on the lid.
  12. Unscrew the lid and tie a nail to the other end of the thread. You want the nail to be hanging above the bottom of the jar by an inch or two, so adjust the height as needed.
  13. Bring your jar outside.
  14. Question: Without breaking the glass or removing the lid, how can you get the nail to drop to the bottom of the jar?

What’s Going On?

Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes by bending the light. When light passes through a different medium (from air to glass, water, a lens…) it changes speed and usually the angle at which it’s traveling. A prism splits incoming light into a rainbow because the light bends as it moves through the prism. A pair of eyeglasses will bend the light to magnify the image.


Exercises


  1. What happened to the leaf? Why?
  2. How did you get the nail to drop?
  3. Which material ignited the quickest?

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What’s Up in the Sky?

Sunday September 1, 2013

Today you get to learn how to read an astronomical chart to find out when the Sun sets, when twilight ends, which planets are visible, when the next full moon occurs, and much more. This is an excellent way to impress your friends.


The patterns of stars and planets stay the same, although they appear to move across the sky nightly, and different stars and planets can be seen in different seasons.


Materials:


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Download Student Worksheet & Exercises


  1. If your chart comes on two pages, you’ll need to cut the borders off at the top and bottom and tape them together so they fit perfectly.
  2. Use your ruler as a straight edge to help locate items as you read the chart.
  3. Print out copies of the almanac by clicking the image of the Skygazer’s Almanac. You can print it full-size on two pages, or size it to fit onto a single page. Since there’s a ton of information on it, it’s best read over two pages. This is an expired calendar  to practice with.
  4. First, note the “hourglass” shape of the chart. Do you see how it’s skinnier in the middle and wider near the ends? Since it’s an astronomical chart that shows what’s up in the sky at night, the nights are shorter during the summer months, so the number of hours the stars are visible is a lot less than during the winter. You’ll find the hours of the night printed across the top and bottom of the chart (find it now) and the months and days of the year printed on the right and left side.
  5. Can you find the summer solstice on June 20? Use your finger and start on the left side between June 17 and June 24. The 20th is between those two dates somewhere. Here’s how you tell exactly…
  6. Look at the entire chart – do you see the little dots that make up little squares all over the chart, like a grid? Each dot in the vertical direction represents one day. There are eight dots on the vertical side of the box.
  7. Let’s say you want to find out what time Neptune rises on June 17. Go back to June 17, which has its own little set of dots. Follow the dots with your finger until you hit the line that says Neptune Rises. Stop and trace it up vertically to the top scale to read just after 11 p.m.
  8. Look again at the dot boxes. Each horizontal dot is 5 minutes apart, and every six dots there is a vertical line representing the half-hour. The line crosses between the second and third dot, so if you lived in a place where you can clearly see the eastern horizon and looked out at 11:07, you’d see Neptune just rising. Since Uranus and Neptune are so far away, though, you’d need a telescope to see them. So let’s try something you can find with your naked eye.
  9. Look at Oct 21. What time does Saturn set? (5:30p.m.).
  10. What other two planets set right afterward? (Mercury at 6:03 p.m. and Mars sets at 7:12 p.m.).
  11. When does Jupiter rise? (7:32 p.m.).
  12. What is Neptune doing that night of Oct. 21? (Neptune transits, or is directly overhead, at 8:07 p.m. and sets at 1:30 a.m.)
  13. What other interesting things happen on Oct. 21? (Betelgeuse, one of the bright stars in the constellation Orion, rises at 9:23 p.m. Sirius, the dog star, rises at 11:06 p.m. The Pleiades, also known as the Seven Sisters, are overhead at 1:42 a.m.)
  14. Let’s find out when the Moon rises on Oct. 21. You’ll find a half circle representing the Moon centered on 11:05 p.m. Which phase is the Moon at? First or third quarter? (First. You can tell if you look at the next couple of days to see if the Moon waxes or wanes. Large circles indicate one of the four main phases of the Moon.)
  15. When does the Sun rise and set for Oct. 21? First, find the nearest vertical set of dots and read the time (5:30 p.m.). Now subtract out the 5-minute dots until you get to the edge. You should read three dots plus a little extra, which we estimate to be 17 minutes. Sunset is at 5:13 p.m. on Oct 21.
  16. Note the fuzzy, lighter areas on both sides of the hourglass. That represents the twilight time when it’s not quite dark, but it’s not daylight either. There’s a thin dashed line that runs up and down the vertical, following the curve of the hourglass offset by about an hour and 35 minutes. That’s the official time that twilight ends and the night begins.
  17. Can you find a meteor shower? Look for a starburst symbol and find the date right in the center. Those are the peak times to view the shower, and it’s usually in the wee morning hours. The very best meteor showers are when there’s also a new Moon nearby.
  18. Notice how Mercury and Venus stay close by the edges of the twilight. You’ll find a half-circle symbol representing the day that they are furthest from the Sun as viewed from the Earth, which is the best date to view it. For Venus, the * indicates the day that it’s the brightest.
  19. What do you think the open circle means at sunset on May 20? (New Moon)
  20. Students that spot the “Sun slow” or “Sun fast” marks on the chart always ask about it. It’s actually rather complicated to explain, but here’s the best way to think about it. Imagine that the vertical timeline running down the center means noon, not midnight. Do you see a second line weaving back and forth across the noon line throughout the year? That’s the line that shows the when the Sun crosses the meridian. On Feb 5, the Sun crosses that meridian at 12:14, so it’s “running slow,” because it “should have” crossed the meridian at noon. This small variation is due to the axis tilt of the Earth. Note that it never gets much more than 15 minutes fast or slow. The wavy line that represents this effect is called the Equation of Time. We’ll be using that later when we make our own sundials and have to correct for the Sun not being where it’s supposed to be.
  21. Look at Mars and Saturn both setting around the same time on Aug. 14. When two event lines cross, you’ll find nearby an open circle with a line coming from the top right side, accompanied by a set of arrows pointing toward each other. This means conjunction, and is a time when you can see two objects at once. Usually the symbol isn’t right at the intersection, because one of the objects is rising or setting and isn’t clearly visible. On Aug. 14, you’ll want to view them a little before they set, so the symbol is moved to a time where you can see them both more clearly.
  22. Important to note: If your area uses daylight savings time, you’ll need to add one hour to the times shown on the chart.
  23. Time corrections for advanced students: This chart was made for folks living on the 40o north latitude and 90o west longitude lines (which is Peoria, Ill.).
    1. If you live near the standardized longitudes for Eastern Time (75o), Central (90o), Mountain (105o) or Pacific (120o), then you don’t have to correct the chart times you read. However, if you live a little west or east of these standardized locations, you need a correction, which looks like this:
      1. For every degree west, add four minutes to the time you read off the chart.
      2. For every degree east, subtract four minutes from the time.
      3. For example, if you lived in Washington, D.C. (which is 77o longitude), note that this is 2o west of the Eastern Time, so you’d add 8 minutes to the time you read off the chart. Memorize your particular adjustment and always use it.
    2. If your latitude isn’t 40o north, then you need to adjust the rise and set times like this:
      1. If you live north of 40o, then the object you are viewing will be in the sky for longer than the chart shows, as it will rise earlier and set later.
      2. If you live south of 40o, then the object you are viewing will be in the sky for less time than the chart shows, as it will rise later and set earlier.
      3. The easiest way to calculate this is to note what time an object should rise, and then watch to see when it actually appears against a level horizon. This is your correction for your location.

    What’s Going On?

    This is one of the finest charts I’ve ever used as an astronomer, as it has so much information all in one place. You’ll find the rise and set times for all eight planets, peak times for annual meteor showers, moon phases, sunrise and set times, and it gives an overall picture of what the evening looks like over the entire year. Kids can clearly see the planetary movement patterns and quickly find what they need each night. I keep one of these posted right by the door for everyone to view all year long.

Exercises


  1.  Is Mercury visible during the entire year?
  2.  In general, when and where should you look for Venus?
  3.  When is the best time to view a meteor shower?
  4.  Which date has the most planets visible in the sky?

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Kepler’s Swinging System

Sunday September 1, 2013
Johannes Kepler, a German astronomer famous for his laws of planetary motion. Check out our Johannes Kepler facts page for more information.
Johannes Kepler, a German astronomer famous for his laws of planetary motion. Check out our Johannes Kepler facts page for more information.

Kepler’s Laws of planetary orbits explain why the planets move at the speeds they do. You’ll be making a scale model of the solar system and tracking orbital speeds.


Kepler’s 1st Law states that planetary orbits about the Sun are not circles, but rather ellipses. The Sun lies at one of the foci of the ellipse. Kepler’s 2nd Law states that a line connecting the Sun and an orbiting planet will sweep out equal areas in for a given amount of time. Translation: the further away a planet is from the Sun, the slower it goes.
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Download Student Worksheet & Exercises


What are the planets in our solar system starting closest to the Sun? On a sheet of paper, write down a planet and label it with the name. Do this for each of the eight planets.


  • Mercury is 0.39 AU (in a rocket it would take 2.7 months to go straight to Mercury from the Sun)
  • Venus is 0.72 AU
  • Earth is 1 AU (in a rocket it would take 7 months to go straight to Earth from the Sun)
  • Mars is 1.5 AU
  • Jupiter is 5.2 AU
  • Saturn is 9.6 AU
  • Uranus is 19.2 AU
  • Neptune is 30.1 AU (in a rocket it would take 18 years to go straight to Neptune from the Sun)

Of course, we don’t travel to planets  in straight lines – we use curved paths to make use of the gravitational pull of nearby objects to slingshot us forward and save on fuel.


  1. Now draw the location of the asteroid belt.
  2. Draw the position of the Kuiper Belt” and ask a student to draw and label it (beyond Neptune).
  3. Where are the five dwarf planets? They are in the Kuiper belt and the asteroid belt:
    • Ceres (in the Asteroid belt, closer to Jupiter than Mars)
    • Pluto (is 39.44 AU from the Sun)
    • Haumea (43.3 AU)
    • Makemake (45.8 AU)
    • Eris. (67.7 AU)

Now for the fun part! You’ll need a group of friends to work together for this lab, so you have at least one student for each planet, one for the Sun, and two for the asteroid belts, and five for the dwarf planets. You can assign additional students to be moons of Earth (Moon), Mars (Phobos and Deimos), Jupiter (assign only 4 for the largest ones: Ganymede, Callisto, Io, and Europa), Saturn (again, assign only 4: Titan, Rhea, Iapetus, and Dione), Uranus (Oberon, Titania), and Neptune (Triton). If you still have extra students, assign one to Charon (Pluto’s binary companion) and one each to Hydra and Nix, which orbit Pluto and Charon. While you ask the students to walk around in a later step, the moons can circle while they orbit.


  1. First, walk outside to a very large area.
  2. Hand the Sun student the measuring tape.
  3. Ask Kuiper Belt student(s) to take the end of the measuring tape and begin walking slowly away from the Sun.
  4. With each student assigned to the distance shown, grab the measuring tape and walk along with it. Please be careful – measuring tapes can have sharp edges! You can use gloves when you grab the tape if you’ve got a sharp steel measuring tape to protect your hands. Ask the Sun to call out the distances periodically so the students know when it’s time to come up.
  5. What do you notice about the distances between the planets? The nearest star is 114.5 miles away!
  6. Ask the students to let go of the measuring tape, except for Neptune and the Sun. Everyone else gathers around you (a safe distance away, as Neptune is going to orbit the Sun).
  7. Using a stopwatch, notice how much time it takes Neptune to walk around the Sun while holding the measuring tape taut. How long did it take for one revolution?
  8. Now ask Mercury to take their position on the tape at the appropriate distance. Time their revolution as they walk around the Sun. How long did it take?
  9. How does this relate to the data you just recorded for Neptune and Mercury? You should notice that the speeds the kids were walking at were probably nearly the same, but the time was much shorter for Mercury. If you could swing them around (instead of having them walk), can you imagine how this would make Mercury orbit at a faster speed than Neptune?
  10. If you have it, you can illustrate how Kepler’s 2nd law works and relate it back to this experiment. Tie a ball to the end of a string and whirling it around in a circle. After a few revolutions, let the string wind itself up around your finger. As the string length shortens, the ball speeds up. As the planet moves inward, the planet’s orbital speed increases. The planet’s speed decreases the further from the Sun it is located.
  11. Ask one of the bigger students to take their position with the measuring tape, reminding them to keep the tape taut no matter what happens. When they start to walk around the Sun, have the Sun move with them a bit (a couple of feet is good). Let the students know that the planet also yanks on the Sun just as hard as the Sun yanks on the planet. Since the planet is much smaller than the Sun, you won’t see as much motion with the Sun.
  12. Optional demonstration to illustrate this idea: take a heavy bag (I like to use oranges) and spin it around as you whirl around in a circle. Do you notice the student leans back a bit to balance themselves as they swing around and around? This is the same principle, just on a smaller scale. The two objects (the bag and the student) are orbiting around a common point, called the center of mass. In our real solar system, the Sun has 99.85% of the mass, so the center of mass lies inside the Sun (although not at the exact center).
  13. Look at the length of your measuring tape. Find the data table you need to use in the tables. Circle the one you’re going to use or cross out the ones you’re not.
  14. Using a stopwatch, time Venus as they walk around the Sun while holding the measuring tape taut. How long did it take for one revolution? (Make sure the Sun doesn’t move much during this process like they did for the demonstration. We’re assuming the Sun is at the center.)
  15. Continue this for all the planets.

What’s Going On?

Johannes Kepler, a German mathematician and astronomer in the 1600s, was one of the key players of his time in astronomy. Among his best discoveries was the development of three laws of planetary orbits. He worked for Tycho Brahe, who had logged huge volumes of astronomical data, which was later passed onto to Kepler. Kepler took this information to design and develop his ideas about the movements of the planets around the Sun.


Kepler’s 1st Law states that planetary orbits about the Sun are not circles, but rather ellipses. The Sun lies at one of the foci of the ellipse. Well, almost. Newton’s Laws of Motion state that the Sun can’t be stationary, because the Sun is pulling on the planet just as hard as the planet is pulling on the Sun. They are yanking on each other. The planet will move more due to this pulling because it is less massive. The real trick to understanding this law is that both objects orbit around a common point that is the center of mass for both objects. If you’ve ever swung a heavy bag of oranges around in a circle, you know that you have to lean back a bit to balance yourself as you swing around and around. It’s the same principle, just on a smaller scale.


In our solar system the Sun has 99.85% of the mass, so the center of mass between the Sun and any other object actually lies inside the Sun (although not at the center).


Kepler’s 2nd Law states that a line connecting the Sun and an orbiting planet will sweep out equal areas in for a given amount of time. The planet’s speed decreases the further from the Sun it is located (actually, the speed varies inversely with the square‐root of the distance, but you needn’t worry about that). You can demonstrate this to the students by tying a ball to the end of a string and whirl it around in a circle. After a few revolutions, let the string wind itself up around your finger. As the string length shortens, the ball speeds up. As the planet moves inward, the planet’s orbital speed increases.


Embedded in the second law are two very important laws: conservation of angular moment and conservation of energy. Although those laws might sound scary, they are not difficult to understand. Angular momentum is distance multiplied by mass multiplied by speed. The angular momentum for one case must be the same for the second case (otherwise it wouldn’t be conserved). As the planet moves in closer to the Sun, the distance decreases. The speed it orbits the Sun must increase because the mass doesn’t change. Just like you saw when you wound the ball around your finger.


Energy is the sum of both the kinetic (moving) energy and the potential energy (this is the “could” energy, as in a
ball dropped from a tower has more potential energy than a ball on the ground, because it “could” move if released). For conservation of energy, as the planet’s distance from the Sun increases, so does the gravitational potential energy. Again, since the energy for the first case must equal the energy from the second case (that’s what conservation means), the kinetic energy must decrease in order to keep the total energy sum a constant value.


Kepler’s 3rd Law is an equation that relates the revolution period with the average orbit speed. The important thing to note here is that mass was not originally in this equation. Newton came along shortly after and did add in the total mass of the system, which fixed the small error with the equation. This makes sense, as you might imagine a Sun twice the size would cause the Earth to orbit faster. However, if we double the mass of the Earth, it does not affect the speed with which it orbits the Sun. Why not? Because the Earth is soooo much smaller than the Sun that increasing a planet’s size generally doesn’t make a difference in the orbital speed. If you’re working with two objects about the same size, of course, then changing one of the masses absolutely has an effect on the other.


Exercises


  1.  If the Sun is not stationary in the center but rather gets tugged a couple of feet as the planet  yanks on it, how do you think this will affect the planet’s orbit?
  2.  If we double the mass of Mars, how do you think this will affects the orbital speed?
  3.  If Mercury’s orbit is normally 88 Earth days, how long do you estimate Neptune’s orbit to  be?

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Star Wobble

Sunday September 1, 2013

How do astronomers find planets around distant stars? If you look at a star through binoculars or a telescope, you’ll quickly notice how bright the star is, and how difficult it is to see anything other than the star, especially a small planet that doesn’t generate any light of its own! Astronomers look for a shift, or wobble, of the star as it gets gravitationally “yanked” around by the orbiting planets. By measuring this wobble, astronomers can estimate the size and distance of larger orbiting objects.


Doppler spectroscopy is one way astronomers find planets around distant stars. If you recall the lesson where we created our own solar system in a computer simulation, you remember how the star could be influenced by a smaller planet enough to have a tiny orbit of its own. This tiny orbit is what astronomers are trying to detect with this method.


Materials


  • Several bouncy balls of different sizes and weights, soft enough to stab with a toothpick
  • Toothpicks

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Download Student Worksheet & Exercises


  1. Does your ball have a number written on it? If so, that’s the weight, and you can skip measuring the weight with a scale.
  2. If not, weigh each one and make a note in the data table.
  3. Take the heaviest ball and spin it on the table. Can you get it to spin in place? That’s like a Sun without any planets around it.
  4. Insert a toothpick into the ball. Now insert the end of the toothpick into the smallest weight ball. Now spin the original ball. What happened?

What’s Going On?

Nearly half of the extrasolar (outside our solar system) planets discovered were found by using this method of detection. It’s very hard to detect planets from Earth because planets are so dim, and the light they do emit tends to be infrared radiation. Our Sun outshines all the planets in our solar system by one billion times.


This method uses the idea that an orbiting planet exerts a gravitational force on the Sun that yanks the Sun around in a tiny orbit. When this is viewed from a distance, the star appears to wobble. Not only that, this small orbit also affects the color of the light we receive from the star. This method requires that scientists make very precise measurements of its position in the sky.


Exercises


  1. For homework tonight, find out how many extrasolar planets scientists have detected so far.
  2. Also for homework, find out the names (they will probably be a string of numbers and letters together) of the 3 most recent extrasolar planet discoveries.

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Eclipses and Transits

Sunday September 1, 2013

It just so happens that the Sun’s diameter is about 400 times larger than the Moon, but the Moon is 400 times closer than the Sun. This makes the Sun and Moon appear to be about the same size in the sky as viewed from Earth. This is also why the eclipse thing is such a big deal for our planet.


You’re about to make your own eclipses as you learn about syzygy. A total eclipse happens about once every year when the Moon blocks the Sun’s light. Lunar eclipses occur when the Sun, Moon, and Earth are lined up in a straight line with the Earth in the. Lunar eclipses last hours, whereas solar eclipses last only minutes.


Materials


  • 2 index cards
  • Flashlight or Sunlight
  • Tack or needle
  • Black paper
  • Scissors

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Download Student Worksheet & Exercises


  1. Trace the circle of your flashlight on the black paper and cut out the circle with paper. This is your Moon. If you are using the Sun instead, cut out a circle about the size of your fist.
  2. Make a tiny hole in one of the index cards by pushing a tack through the middle of the card.
  3. Hold the punched index card a couple inches above the plain one and shine your light through the hole so that a small disk appears on the lower card. Move the cards closer or further until it comes into focus. The disk of light is the Sun.
  4. Ask your lab partner to slowly move the black paper disk in front of your light as you watch what happens to the Sun on the bottom index card.
  5. Continue moving the black paper until you can see the Sun again.
  6. Where does your circle need to be in order to create an annular eclipse? A partial eclipse?
  7. How would you simulate Mercury transiting the Sun? What would you use?
  8. Fill out the table.

What’s Going On?

An eclipse is when one object completely blocks another. If you’re big on vocabulary words, then let the students know that eclipses are one type of syzygy (a straight line of three objects in a gravitational system, like the Earth, Moon, and Sun). A lunar eclipse is when the Moon moves into the Earth’s shadow, making the Moon appear copper-red.



A solar eclipse is when the Moon’s shadow crawls over the Earth, blocking out the Sun partially or completely. There are three kinds of solar eclipses. A total eclipse blocks the entire Sun, whereas in a partial eclipse the Moon appears to block part, but not all of the Sun’s disk. An annular eclipse is when the Moon is too far from Earth to completely cover the Sun, so there’s a bright ring around the Moon when it moves in front of the Sun. It just so happens that the Sun’s diameter is about 400 times larger than the Moon, but the Moon is 400 times closer than the Sun. This makes the Sun and Moon appear to be about the same size in the sky as viewed from Earth. This is also why the eclipse thing is such a big deal for our planet. Transits are where the disk of a planet (like Venus) passes like a small shadow across the Sun. Io transits the surface of Jupiter. In rare cases, one planet will transit another. These are rare because all three objects must align in a straight line.



Astronomers use this method to detect large planets around distant bright stars. If a large planet passes in front of its star, the star will appear to dim slightly. Note: A transit is not an occultation, which completely hides the smaller object behind a larger one. Exercises


  1. What other planets can have eclipses?
  2. Which planets transit the Sun?
  3. How is a solar eclipse different from a lunar eclipse?
  4. What phase can a lunar eclipse occur?
  5.  Can a solar eclipse occur at night?

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Meteorites

Sunday September 1, 2013

A meteoroid is a small rock that zooms around outer space. When the meteoroid zips into the Earth’s atmosphere, it’s now called a meteor or “shooting star”. If the rock doesn’t vaporize en route, it’s called a meteorite as soon as it whacks into the ground. The word meteor comes from the Greek word for “high in the air.”


Meteorites are black, heavy (almost twice the normal rock density), and magnetic. However, there is an Earth-made rock that is also black, heavy, and magnetic (magnetite) that is not a meteorite. To tell the difference, scratch a line from both rocks onto an unglazed tile. Magnetite will leave a mark whereas the real meteorite will not.


Materials


  • White paper
  • Strong magnet
  • Handheld magnifying glass (optional)

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Download Student Worksheet & Exercises


  1. Imagine you are going on a rock hunt. You are to find which rocks are meteorites and which are Earth rocks. If you don’t have access to rock samples, just watch the experiment video of the different rock samples. If you’d like to make your own sample collection, here are some ideas:
    1. 8-10 different rocks, including pumice (from a volcano), lodestone (a naturally magnetized piece of magnetite, and often mistaken for meteorites), a fossil, tektite (dry fused glass), pyrite (also known as fool’s gold), marble (calcite or dolomite), and a couple of different kinds of real meteorites (iron meteorite, stony meteorite, etc.) Also add to your bag an unglazed tile and a magnet.
  2. As you watch the experiment video, record your observations on your data sheet.
    1. Since nearly all meteorites have lots of iron, they are usually attracted to a magnet. However, lodestone is an Earth rock that also has a lot of iron. Iron is heavy, and meteorites contain a lot of iron. When looking through the possibilities, remove any lightweight rocks, as they are not usually meteorites.
    2. Meteorites are small. Most never get big enough or hot enough for metal to sink into the core, so the majority are mixed with rock and dust (stony meteorites). The few that do get big and form metal cores are called iron meteorites.
    3. Most meteorites come from the Asteroid Belt. Some meteorites get a dark crust. While others look like splashed metal. They are all dark, at least on the outside. Remove any light-colored rocks.
    4. Rocks that have holes vaporize or explode when they go through the atmosphere, they don’t burn up. Only strong space rocks without holes make it to the ground. Remove any porous rocks.
    5. The ones you have left are either meteorites or lodestone. To tell the difference, scratch a line from both rocks onto an unglazed tile. Magnetite (lodestone) will leave a mark whereas the real meteorite will not.

Finding Meteorites


  1. Place a sheet of white paper outside on the ground. Do this in the morning when you first start up class.
  2. After a few hours (like just before lunchtime), your paper starts to show signs of “dust.”
  3. Carefully place a magnet underneath the paper, and see if any of the particles move as you wiggle the magnet. If so, you’ve got yourself a few bits of space dust.
  4. Use a magnifying lens to look at your space meteorites up close.

What’s Going On?

94% of all meteorites that fall to the Earth are stony meteorites. Stony meteorites will have metal grains mixed with the stone that are clearly visible when you look at a slice.


Iron meteorites make up only 5% of the meteorites that hit the Earth. However, since they are stronger, most of them survive the trip through the atmosphere and are easier to find since they are more resistant to weathering. More than half the meteorites we find are iron meteorites. They are the one of the densest materials on Earth. They stick strongly to magnets and are twice as heavy as most Earth rocks. The Hoba meteorite in Namibia weighs 50 tons.


Since nearly all meteorites have lots of iron, they are usually attracted to a magnet. However, lodestone is an Earth rock that also has a lot of iron. Iron is heavy, and meteorites contain a lot of iron. When looking through the possibilities, remove any lightweight rocks, as they are not usually meteorites.


Meteorites are small. Most never get big enough or hot enough for metal to sink into the core, so the majority are mixed with rock and dust (stony meteorites). The few that do get big and form metal cores are called iron meteorites.


Most meteorites come from the Asteroid Belt. Some meteorites get a dark crust, while others look like splashed metal. They are all dark, at least on the outside.


Rocks that have holes vaporize or explode when they go through the atmosphere, they don’t burn up. Only strong space rocks without holes make it to the ground.


Every year, the Earth passes through the debris left behind by comets. Comets are dirty snowballs that leave a trail of particles as they orbit the Sun. When the Earth passes through one of these trails, the tiny particles enter the Earth’s atmosphere and burn up, leaving spectacular meteor showers for us to watch on a regular basis. The best meteor showers occur when the moon is new and the sky is very dark.


Meteorites are black, heavy (almost twice the normal rock density), and magnetic. However, there is an Earth-made rock that is also black, heavy, and magnetic (magnetite) that is not a meteorite. To tell the difference, scratch a line from both rocks onto an unglazed tile (or the bottom of a coffee mug or the underside of the toilet tank). Magnetite will leave a mark, whereas the real meteorite will not.


If you find a meteorite, head to your nearest geology department at a local university or college and let them know what you’ve found. In the USA, if you find a meteorite, you get to keep it… but you might want to let the experts in the geology department have a thin slice of it to see what they can figure out about your particular specimen.


Exercises


  1.   Are meteors members of the solar system?
  2.  How big are meteors?
  3. Why do we have meteor showers at predictable times of the year?

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Solar Rotation

Sunday September 1, 2013

You are going to start observing the Sun and tracking sunspots across the Sun using one of two different kinds of viewers so you can figure out how fast the Sun rotates. Sunspots are dark, cool areas with highly active magnetic fields on the Sun’s surface that last from hours to months. They are dark because they aren’t as bright as the areas around them, and they extend down into the Sun as well as up into the magnetic loops.


Materials


  • Tack and 2 index cards  OR a Baader film  (this works better than the tacks and card)

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Download Student Worksheet & Exercises


We’re going to learn two different ways to view the Sun. First is the pinhole projector and the second is using a special film called a Baader filter. The quickest and simplest way to do this is to build a super-easy pinhole camera that projects an image of the Sun onto an index card for you to view.


If the Sun is not available, you can use images from a satellite that’s pointed right at the Sun while orbiting around the Earth called “SOHO.” SOHO gets clear, unobstructed views of the Sun 24 hours a day, since it’s above the atmosphere of the Earth. Download the very latest image of the Sun from NASA’s SOHO page (choose the SDO/HMI Continuum filter for the best sunspot visibility) and hand them out to the students to track the sunspots.


Solar Pinhole Projector


  1. With your tack, make a small hole in the center of one of the cards.
  2. Stack one card about 12″ above the other and go out into the Sun.
  3. Adjust the spacing between the cards so a sharp image of the Sun is projected onto the lower paper.
  4. The Sun will be about the size of a pea.
  5. You can experiment with the size of the hole you use to project your image.
  6. What happens if your hole is really big? Too small?
  7. What if you bend the lower card while viewing? What if you punch two holes? Or three?

Baader Filter


  1. Using a Baader filter, you’re going to look straight through the filter right at the Sun. Put the filter between you and the Sun, right up close to your eye and look through it. It takes a little while to get the hang of seeing the Sun through this filter, but it’s totally worth it.

Taking Data:


  1. Using either the Baader filter or the solar pinhole projector (or both), you will track the sunspot activity using the mapping grid. You will be charting the Sun for two weeks using the mapping grid.
  2. Each day, step outside at the same time each day and look at the Sun using one of the two filter methods.
  3. Draw what you see on the mapping grid.
  4. Draw the sunspot(s) with the date of the month next to it. For example, on March 13, write a “13” right next to the sunspot picture you drew. If there’s more than one sunspot, pick the largest one to track. If you’d like to track all of them, label them A-13, B-13, C-13…etc. The next day, label the set A-14, B-14, C-14. For multiple sunspots, use one mapping grid per day.

What’s Going On?

The Sun rotates differentially, since it’s not solid but rather a ball of hot gas and plasma. The equator rotates faster than the poles, and in one of the experiments in this section, you’ll actually get to measure the Sun’s rotation. This differential rotation causes the magnetic fields to twist and stretch. The Sun has two magnetic poles (north and south) that swap every 11 years as the magnetic fields reach their breaking point, like a spinning top that’s getting tangled up in its own string. When they flip, it’s called “solar maximum,” and you’ll find the most sunspots dotting the Sun at this time.


You know you’re not supposed to look at the Sun, so how can you study it safely? I’m going to show you how to observe the Sun safely using a very inexpensive filter. I actually keep one of these in the glove box of my car so I can keep track of certain interesting sunspots during the week!


The visible surface of the Sun is called the photosphere, and is made mostly of plasma (electrified gas) that bubbles up hot and cold regions of gas. When an area cools down, it becomes darker (called sunspots). Solar flares (massive explosions on the surface), sunspots, and loops are all related the Sun’s magnetic field. While scientists are still trying to figure this stuff out, here’s the latest of what they do know…


The Sun is a large ball of really hot gas – which means there are lots of naked charged particles zipping around. And the Sun also rotates, but the poles and the equator move and different speeds (don’t forget – it’s not a solid ball but more like a cloud of gas). When charged particles move, they make magnetic fields (that’s one of the basic laws of physics). And the different rotation rates allow the magnetic fields to “wind up” and cause massive magnetic loops to eject from the surface, growing stronger and stronger until they wind up flipping the north and south poles of the Sun (called ‘solar maximum’). The poles flip every 11 years.


The Sun rotates, but because it’s not a solid body but a big ball of gas, different parts of the Sun rotate at different speeds. The equator (once every 27 days) spins faster than the poles (once every 31 days). Sunspots are a great way to estimate the rotation speed.


Sunspots usually appear in groups and can grow to several times the size of the Earth. Galileo was the first to record solar activity in 1613, and was amazed how spotty the Sun appeared when he looked at the projected image on his table.


There have been several satellites especially created to observe the Sun, including Ulysses (launched 1990, studied solar wind and magnetic fields at the poles), Yohkoh (1991-2001, studied X-rays and gamma radiation from solar flares), SOHO (launched 1995, studies interior and surface), and TRACE (launched 1998, studies the corona and magnetic field). And as of August 2017, Astronomers have figured out that the surface of the sun rotates slower than its core (by about four times as much!) by studying surface acoustic waves in the sun’s atmosphere.


Exercises


  1.  How many longitude degrees per day does the sunspot move?
  2.  Do all sunspots move at the same rate?
  3.  Did some of the sunspots change size or shape, appear or disappear?

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Black Hole Bucket

Sunday September 1, 2013

What comes to mind when you think about empty space? (You should be thinking: “Nothing!”) One of Einstein’s greatest ideas was that empty space is not actually nothing – it has energy and can be influenced by objects in it. It’s like the T-shirt you’re wearing. You can stretch and twist the fabric around, just like black holes do in space.


Today, you will get introduced to the idea that gravity is the structure of spacetime itself. Massive objects curve space. How much space curves depends on how massive the object is, and how far you are from the massive object.


Materials


  • Two buckets with holes in the bottom
  • 2 bungee cords
  • 3 different sizes of marbles
  • 2.5 lb weight
  • 0.5 lb weight
  • 3 squares of stretchy fabric
  • Rubber band
  • 4 feet of string
  • Fishing bobber
  • Drinking straws
  • Softball
  • Playdough (optional)

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Download Student Worksheet & Exercises


Making the Buckets Ready for the Lab


  1. What is gravity? How does it work? That’s what today’s lab is all about.
  2. Stretch the bungee cord around the circumference of the bucket. Do this for both buckets.
  3. On one bucket, tuck in the stretchy fabric under the cord. If your cords are loose, tie another knot near the end so they fit snugly around the bucket. The fabric is stretched like a drum head. This is the “fabric of space” – it’s around us everywhere.
  4. Push the bottom of the bobber so the hook opens on the other end. Push your string in.
  5. Place it in the center of the squares of fabric. Fasten it with your rubber band.
  6. Thread the ends of your string through the bottom holes of your second bucket and tie it securely on the bottom.
  7. Tuck in your corners under the bungee cord. This is your black hole bucket.
  8. The first lab uses two buckets, neither of which is a black hole. We’re going to convert the black hole bucket to a regular spacetime fabric bucket. For now, place a second piece of fabric over the black hole bucket and tuck it under the cord so that it looks like the first bucket you used.
  9. Now, we’re ready for our lab.

Exploring How Space Curves


  1. Place a mid-sized weight in the middle of one of the buckets. What happens to the fabric when you put a weight on the fabric?
  2. Place the heavy 2.5lb lead weight in the center of the fabric of the second bucket. Did it curve more or less than the first weight?
  3. The heavier weight is like the Sun, and the lighter weight is like the Earth. Which has more mass?
  4. Which has more gravitational attraction?
  5. Is space more or less curved further from the object?
  6. Where is space curved the most?
  7. Grab your marbles. These are your space probes. If we place one probe at the edge of each bucket, which do you expect it to fall toward the middle faster?
  8. Why?
  9. This is what we mean when we say the force of gravity depends on how much mass something has, since mass curves space. More massive objects curve space more, so the gravitational attraction is more with more massive objects.
  10. Take two marbles of different sizes and drop them at the same time onto the edge of the bucket. You can drop them on opposite sides so they don’t knock into each other. What happens?
  11. The Moon is like a giant marble. Why doesn’t it fall to Earth?
  12. Why is it orbiting?
  13. Remove all weights from the fabric. Roll a marble across the surface (do it slowly without bouncing – planet’s don’t bounce!). Does it roll straight or curved?
  14. Place the heavy weight on the fabric. Try to make the marble go in a straight line. Did it work?
  15. Can you roll the marble so that it escapes from the weight that represents the Sun?
  16. In the second bucket, place a smaller weight and do steps 23 and 24 again. How is this different?
  17. Planets orbit the Sun because space is curved around the Sun. The Moon orbits the Earth without falling in because space is curved around Earth. How fast the moon moves through space and how much the Earth curves space depends on the Earth’s mass and how far away the moon is.
  18. If the Moon was in closer to the Earth, would it have to move faster or slower to maintain its orbit?
  19. Let’s find out: Place two marbles, one closer to the weight and one near the edge of the bucket, and make them orbit the weight. Which one orbits faster? Why?
  20. Replace the weight in the second bucket with a lightweight mass. Now, what if Earth was less massive? How would this change the Moon’s orbit?
  21. Notice this: When you roll a ball in orbit around a weight, do you see the weight move slightly also? All orbiting objects yank on each other. The Moon pulls on the Earth just as the Earth pulls on the Moon. All massive objects cause space to move: planets, stars, black holes, comets, etc.

Exploring Black Holes


  1. Place a weight in each bucket, one representing the Earth and the other representing the Moon.
  2. Place a marble next to each weight. These marbles are your rocket ships. Do you think that you can launch your rockets and escape the pull of gravity? Grab a straw and try to blow the marble away from the weight (launch the rocket off the Earth and moon). What happened? Why?
  3. What if we start the rockets in space? Do you think you can escape the pull of the objects now? Start the marbles orbiting and then blow them the straws. Can you fire your rockets at the right time to get your rockets to escape the orbit?
  4. Let’s launch a probe out of a black hole! Remove the fabric from the black hole bucket and place a marble in the black hole. Can you use your straw to blow the marble out of the black hole?
  5. Let’s see the difference between the Sun and a black hole. Grab an 8-ounce weight and the softball. These have the same mass, but they are different sizes. The softball is the Sun, and the weight is the black hole. Which is going to curve space more when you place it on the fabric? Guess before you try it:
  6. Replace the fabric over the black hole bucket.
  7. Place the softball on one of the buckets, and the 8-ounce weight on the other bucket.
  8. Roll a marble near the edge of each bucket. This is where our Earth would be orbiting. Notice that although the weight curves space more near it, at the edge, the curvature is the same. So if the Sun were suddenly replaced by a black hole of the same mass, the Earth wouldn’t notice it (gravitationally, at least. It would get dark and cold, though.),
  9. Remove the second fabric from the black hole bucket so you have the vortex exposed.
  10. Take two marbles and start them orbiting at the edge of the black hole. What happens? Why?
  11. Make a rocket shape out of clay or playdough. Bring the rocket close to the black hole bucket and get prepared to show your teammates what happens if it goes into the black hole. First, it stretches (pull the rocket into a longer shape), then it gets shredded (crumple it up) and finally added to the black hole’s mass (shove it into the bucket).

What’s Going On?

Massive objects are truly massive. If our solar system was the size of a quarter, the Milky Way would be the size of North America.


The Milky Way has an estimated 100 billion stars. That’s hard to imagine, so try this: Imagine a football field piled 4’ deep in birdseed. Now scatter those seeds over North America and space them 25 miles deep. Each seed is a Sun. Stars are very far apart!


If the mass of the Sun was one birdseed, then the mass of a black hole would be 22 gallons of birdseed shoved into the volume of a single birdseed.


It’s time to explore how black holes interact with the universe. There are four animations to watch. Let the students know that these are scientific simulations which used actual data to create them – they are not artist’s concepts or fantasy. They are based on solid physics. The reason they are animations is because these videos happen over such a long period of time, and our view is limited in some cases.


Exercises


  1.  What is the event horizon?
  2.  Does a more massive object curve space more or less than a smaller object? What does this    mean for the gravitational field?
  3.  Does an object feel more or less gravitational attraction as the object moves closer to a  massive object?
  4.  Where is space most curved?
  5.  What is mass?

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Sky in a Jar

Sunday September 1, 2013

Have you ever wondered why the sky is blue? Or why the sunset is red? Or what color our sunset would be if we had a blue giant instead of a white star? This lab will answer those questions by showing how light is scattered by the atmosphere.


Particles in the atmosphere determine the color of the planet and the colors we see on its surface. The color of the star also affects the color of the sunset and of the planet.


Materials


  • Glass jar
  • Flashlight
  • Fingernail polish (red, yellow, green, blue)
  • Clear tape
  • Water
  • Dark room
  • Few drops of milk

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Download Student Worksheet & Exercises


  1. Make your room as dark as possible for this experiment to work.
  2. Make sure your label is removed from the glass jar or you won’t be able to see what’s going on.
  3. Fill the clear glass jar with water.
  4. Add a teaspoon or two of milk (or cornstarch) and swirl.
  5. Shine the flashlight down from the top and look from the side – the water should have a bluish hue. The small milk droplets scatter the light the same way our atmosphere’s dust particles scatter sunlight.
  6. Try shining the light up from the base – where do you need to look in order to see a faint red/pink tint? If not, it’s because you are looking for hues that match our real atmosphere, and the jar just isn’t that big, nor is your flashlight strong enough! Instead, look for a very slight color shift. If you do this experiment after being in the dark for about 10 minutes (letting your eyes adjust to the lack of light), it is easier to see the subtle color changes. Just be careful that you don’t let the brilliant flashlight ruin your newly acquired night-vision, or you’ll have to start the 10 minutes all over again.
  7. If you are still having trouble seeing the color changes, shine your light through the jar and onto an index card on the other side. You should see slight color changes on the white card.
  8. Cover the flashlight lens with clear tape.
  9. Paint on the tape (not the lens) the fingernail polish you need to complete the table.
  10. Repeat steps 7-9 and record your data.

What’s Going On?

Why is the sunset red? The colors you see in the sky depends on how light bounces around. The red/orange colors of sunset and sunrise happen because of the low angle the Sun makes with the atmosphere, skipping the light off dust and dirt (not to mention solid aerosols, soot, and smog). Sunsets are usually more spectacular than sunrises, as more “stuff” floats around at the end of the day (there are less particles present in the mornings). Sometimes just after sunset, a green flash can be seen ejecting from the setting Sun.


The Earth appears blue to the astronauts in space because the shorter, faster wavelengths are reflected off the upper atmosphere. The sunsets appear red because the slower, longer wavelengths bounce off the clouds.Sunsets on other planets are different because they are farther (or closer) to the Sun, and also because they have a different atmosphere than planet Earth. The image shown here is a sunset on Mars. Uranus and Neptune appear blue because the methane in the upper atmosphere reflects the Sun’s light and the methane absorbs the red light, allowing blue to bounce back out.


sunset-mars


Exercises


  1. What colors does the sunset go through?
  2. Does the color of the light source matter?

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Binary Planetary Systems

Sunday September 1, 2013

A binary system exists when objects approach each other in size (and gravitational fields), the common point they rotate around (called the center of mass) lies outside both objects and they orbit around each other. Astronomers have found binary planets, binary stars, and even binary black holes.


The path of a planet around the Sun is due to the gravitational attraction between the Sun and the planet. This is true for the path of the Moon around the Earth, and Titan around Saturn, and the rest of the planets that have an orbiting moon.


Materials


  • Soup cans or plastic containers with holes punched (like plastic yogurt containers, butter tubs, etc.)
  • String
  • Water
  • Sand
  • Rocks
  • Pebbles
  • Baking soda
  • Vinegar

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Download Student Worksheet & Exercises


  1. Thread one end of the string through one of the holes and tie a strong knot. Really strong.
  2. Tie the other end through the other hole and tie off.
  3. Go outside.
  4. Fill your can partway with water.
  5. Move away from everyone before you start to swing your container in a gentle circle. As you spin faster and faster, notice where the water is inside the container.
  6. Now empty out the water and replace it with rocks. Spin again and fill out the data table.
  7. To make carbon dioxide gas, you’ll need to work with another lab team. Cover the bottom of your container with baking soda. Add enough vinegar so that the bubbles reach the top without overflowing. Wait patiently for the bubbles to subside. You now have a container filled with carbon dioxide gas (and a little sodium acetate, the leftovers from the reaction). Carefully pour this into the empty container from the other lab team. They can spin again and record their results. When they are done, borrow their container and give them yours so they can fill it for you.

What’s Going On?

The path of a planet around the Sun is due to the gravitational attraction between the Sun and the planet. This is true for the path of the Moon around the Earth, and Titan around Saturn, and the rest of the planets that have an orbiting moon.


Charon and Pluto orbit around each other due to their gravitational attraction to each other. However, Charon is not the moon of Pluto, as originally thought. Pluto and Charon actually orbit around each other. Pluto and Charon also are tidally locked, just like the Earth-Moon system, meaning that one side of Pluto is always faces the same side of Charon.


Imagine you have a bucket half full of water. Can you tilt a bucket completely sideways without spilling a drop? Sure thing! You can swing it by the handle, and even though it’s upside down at one point, the water stays put. What’s keeping the water inside the bucket?


Before we answer this, imagine you are a passenger in a car, and the driver is late for an appointment. They take a turn a little too fast, and you forgot to fasten your seat belts. The car makes a sharp left turn. Which way would you move in the car if they took this turn too fast? Exactly – you’d go sliding to the right. So, who pushed you?


No one! Your body wanted to continue in a straight line, but the car is turning, so the right side car door keeps pushing you to turn you in a curve – into the left turn. The car door keeps moving in your way, turning you into a circle. The car door pushing on you is called centripetal force. Centripetal means “center-seeking.” It’s the force that points toward the center of the circle you’re moving on. When you swing the bucket around your head, the bottom of the bucket is making the water turn in a circle and not fly away. Your arm is pulling on the handle of the bucket, keeping it turning in a circle and not letting it fly away. That’s centripetal force.


Think of it this way: If I throw a ball in outer space, does it go in a straight line or does it wiggle all over the place? Straight line, right? Centripetal force is the force needed to keep an object following a curved path.


Remember how objects will travel in a straight line unless they bump into something or have another force acting on them, such as gravity, drag force, and so forth? Well, to keep the bucket of water swinging in a curved arc, the centripetal force can be felt in the tension experienced by the handle (or your arm, in our case). Swinging an object around on a string will cause the rope to undergo tension (centripetal force), and if your rope isn’t strong enough, it will snap and break, sending the mass flying off in a tangent (straight) line until gravity and drag force pull the object to a stop. This force is proportional to the square of the speed – the faster you swing the object, the higher the force.


Exercises


  1. How is spinning the container like Pluto and Charon?
  2. What would happen if we cut the string while you are spinning? Which way would the container go?
  3. What happens if we triple the size of your container and what’s inside of it?

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Planetary Magnetic Fields

Sunday September 1, 2013

You’re going to use a compass to figure out the magnetic lines of force from a magnet by mapping the two different poles and how the lines of force connect the two. A magnetic field must come from a north pole of a magnet and go to a south pole of a magnet (or atoms that have turned to the magnetic field.)


Compasses are influenced by magnetic lines of force. These lines are not necessarily straight. When they bend, the compass needle moves. The Earth has a huge magnetic field. The Earth has a weak magnetic force. The magnetic field comes from the moving electrons in the currents of the Earth’s molten core. The Earth has a north and a south magnetic pole which is different from the geographic North and South Pole.


Materials


  • Bar magnet
  • Horseshoe magnet
  • Circular (disk) magnet
  • Compass
  • String
  • Ruler

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Download Student Worksheet & Exercises


    1. Tie a string around your magnet.
    2. Bring it close to the compass.
    3. Which end is the north end of your magnet? Label it with a pencil right on the magnet.
    4. Flip the magnet around by twisting the string so that the compass flips to the opposite pole. Label the opposite site of the magnet with the appropriate letter (N or S).
    5. Bring a second magnet close to the first one. What happens when you bring two opposite poles together? What if the poles are the same?
      Now untie or cut the string for the next part of your lab.
    6. Lay a piece of paper on your desk.
    7. Place the magnet in the middle of the paper and trace the outline.
    8. Draw 12 dots (just like on a clock) all the way around the magnet. These are the locations where you will place your compass, so make sure that they are close enough to the magnet so the magnet influences the compass.
    9. Place your compass on one of the dots and look at the direction the arrow is pointing. Remove the compass and draw that exact arrow direction right over your dot. Do this for all 12 dots.
    10. Draw another ring of dots an inch or two out from the first ring and repeat step 9.
    11. Repeat steps 6-10 with a circular magnet on a new sheet of paper.
    12. Repeat steps 6-10 for the horseshoe magnet on another sheet of paper.

What’s Going On?

Right under your feet, there’s a magnet. Go ahead take a look. Lift up your feet and see what’s under there. Do you see it? It’s huge! In fact, it’s the largest magnet on the Earth. As a matter of fact, it is the Earth! That’s right; the Earth is one huge, gigantic, monolithic magnet! We’re going to use a magnet to substitute for the Earth and plot out the magnetic field lines.


The magnetic pole which was attracted to the Earth’s North Pole was labeled as the Boreal or “north-seeking pole” in the 1200s, which was later shortened to “north pole.” To add to the confusion, geologists call this pole the North Magnetic Pole.


Exercises


  1.  How are the lines of force different for the two magnets?
  2. How far out (in inches measured from the magnet) does the magnet affect the compass?
  3. What makes the compass move around?
  4. Do you think the compass’s north–south indicator is flipped, or the Earth’s North Pole where the South Pole is? How do you know?

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Seasons

Sunday September 1, 2013

One common misconception is that the seasons are caused by how close the Earth is to the Sun. Today you get to do an experiment that shows how seasons are affected by axis tilt, not by distance from the Sun. And you also find out which planet doesn’t have sunlight for 42 years.


The seasons are caused by the Earth’s axis tilt of 23.4o from the ecliptic plane.


Materials


  • Bright light source (not fluorescent)
  • Balloon
  • Protractor
  • Masking tape
  • 2 liquid crystal thermometers (optional)
  • Ruler, yardstick or meter stick
  • Marker

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Download Student Worksheet & Exercises


  1. For a light source, try lamps with 100W bulbs (without lamp shades). Make sure there’s room to walk all the way around it. You’ll want to circle the lamp at a distance of about 2 feet away.
  2. Mark on the floor with tape and label the four positions: winter, spring, summer, and fall. They should be at the 12, 3, 6, and 9 o’clock positions. Winter is directly across from summer. The Earth rotates counterclockwise around the Sun when viewed from above.
  3. Blow up your balloon so it’s roughly round-shaped (don’t blow it up all the way). Mark and label the north and south poles with your marker. Draw an equator around the middle circumference.
  4. The Earth doesn’t point its north pole straight up as it goes around the Sun. It’s tilted over 23.4o. here’s how you find this point on your balloon:
    1. Put the South Pole mark on the table, with north pointing straight up. Find the midway point between the equator and the North Pole and make a tiny mark. This is the 45o latitude point. You’ll need this to find the 23o mark.
    2. Find the midway point between the 45o and the North Pole and make another mark, larger this time and label it with 23o. When this mark is pointing up, the Earth is tilted over the right amount.
    3. You’ll need to do this three more times so you can draw a line connecting the dots. You want to draw the latitude line at 23o so you can rotate the balloon as you move around to the different seasons. The line will always be pointed up.
  5. Place the thermometers on the balloon at these locations:
    1. Find the halfway point between the South Pole and the equator. Put one thermometer on this mark.
    2. Put the other thermometer on the northern hemisphere’s 45o mark from above.
  6. Make sure your lamp is facing the balloon as you stand on summer. Let the balloon be heated by the lamp for a couple of minutes and then record the temperature in the data table.
  7. Rotate the lamp to point to fall. Move your balloon to fall, rotating the balloon so that the thermometers are facing the lamp. Wait a few more minutes and take another reading.
  8. Rotate the lamp to point to winter. Move your balloon to winter, rotating the balloon so that the thermometers are facing the lamp. Wait a few more minutes and take another reading.
  9. Rotate the lamp to point to spring. Move your balloon to spring, rotating the balloon so that the thermometers are facing the lamp. Wait a few more minutes and take another reading. You’ve completed a data set for planets with an axis tilt of about 23o, which includes the Earth, Mars, Saturn and Neptune.
  10. Repeat steps 1-9 for Mercury. Note that Mercury does not have an axis tilt, so the North Pole really points straight up. Jupiter (3.1o axis tilt) and Venus (2.7o) are very similar. The Moon’s axis tilt is 6.7o, so you can approximate these four objects with a 0o axis tilt.
  11. Repeat steps 1-9 for Uranus. Since the axis tilt is 97.8o, you can approximate this by pointing the north pole straight at the Sun during summer (90o axis tilt). The orbit for Uranus is 84 years, which means 21 years passes between each season. The north pole will experience continued sunlight for 42 years from spring through fall, then darkness for 42 years.

What’s Going On?

The north and south poles only experience two seasons: winter and summer. During a South Pole winter, the Sun will not rise for several months, and also the Sun does not set for several months in the summer. We go into more detail about how this works in a later lesson entitled: Star Trails and Planet Patterns.


At the equator, there’s a wet season and a dry season due to the tropical rain belt. Since the equator is always oriented at the same position to the Sun, it receives the same amount of sunlight and always feels like summer.


The changing of the seasons is caused by the angle of the Sun. For example, in June during summer solstice, the Sun is high in the sky for longer periods of time, which makes warmer temperatures for the Northern Hemisphere. During the December winter solstice, the Sun spends less time in the sky and is positioned much lower. This makes the winters colder. (Don’t forget that seasons are also affected by oceans and winds, though this is out of the scope of this particular activity.)


Exercises


  1. What is the main reason we have seasons on Earth?
  2. Why are there no sunsets on Uranus for decades?
  3. Are there seasons on Venus?

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Watch Your Weight

Sunday September 1, 2013

If you could stand on the Sun without being roasted, how much would you weigh? The gravitational pull is different for different objects. Let’s find out which celestial object you’d crack the pavement on, and which your lightweight toes would have to be careful about jumping on in case you leapt off the planet.


Weight is nothing more than a measure of how much gravity is pulling on you. Mass is a measure of how much stuff you’re made out of. Weight can change depending on the gravitational field you are standing in. Mass can only change if you lose an arm.


Materials


  • Scale to weigh yourself
  • Calculator
  • Pencil

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Download Student Worksheet & Exercises


  1. We need to talk about the difference between weight and mass. In everyday language, weight and mass are used interchangeably, but scientists know better.
  2. Mass is how much stuff something is made out of. If you’re holding a bowling ball, you’ll notice that it’s hard to get started, and once it gets moving, it needs another push to get it to stop. If you leave the bowling ball on the floor, it stays put. Once you push it, it wants to stay moving. This “sluggishness” is called inertia. Mass is how much inertia an object has.
  3. Every object with mass also has a gravitational field, and is attracted to everything else that has mass. The amount of gravity something has depends on how far apart the objects are. When you step on a bathroom scale, you are reading your weight, or how much attraction is between you and the Earth.
  4. If you stepped on a scale in a spaceship that is parked from any planets, moons, black holes, or other objects, it would read zero. But is your mass zero? No way. You’re still made of the same stuff you were on Earth, so your mass is the same. But you’d have no weight.
  5. What is your weight on Earth? Let’s find out now.
  6. Step on the scale and read the number. Write it down.
  7. Now, what is your weight on the Moon? The correction factor is 0.17. So multiply your weight by 0.17 to find what the scale would read on the Moon.
  8. For example, if I weigh 100 pounds on Earth, then I’d weight only 17 pounds on the Moon. If the scale reads 10 kg on Earth, then it would read 1.7 kg on the Moon.

What’s Going On?

Weight is nothing more than a measure of how much gravity is pulling on you. This is why you can be “weightless” in space. You are still made of stuff, but there’s no gravity to pull on you so you have no weight. The larger a body is, the more gravitational pull (or in other words the larger a gravitational field) it will have.


The Moon has a fairly small gravitational field (if you weighed 100 pounds on Earth, you’d only be 17 pounds on the Moon).The Earth’s field is fairly large and the Sun has a HUGE gravitational field (if you weighed 100 pounds on Earth, you’d weigh 2,500 pounds on the Sun!).


As a matter of fact, the dog and I both have gravitational fields! Since we are both bodies of mass, we have a gravitational field which will pull things toward us. All bodies have a gravitational field. However, my mass is so small that the gravitational field I have is miniscule. Something has to be very massive before it has a gravitational field that noticeably attracts another body.


So what’s the measurement for how much stuff you’re made of? Mass. Mass is basically a weightless measure of how much matter makes you you. A hamster is made of a fairly small amount of stuff, so she has a small mass. I am made of more stuff, so my mass is greater than the hamster’s. Your house is made of even more stuff, so its mass is greater still. So, here’s a question. If you are “weightless” in space, do you still have mass? Yes, the amount of stuff you’re made of is the same on Earth as it is in your space ship. Mass does not change, but since weight is a measure for how much gravity is pulling on you, weight will change.


Did you notice that I put weightless in quotation marks? Wonder why?


Weightlessness is a myth! Believe it or not, one is never weightless. A person can be pretty close to weightless in very deep space, but the astronauts in a space ship actually do have a bit of weight.


Think about it for a second. If a space ship is orbiting the Earth, what is it doing? It’s constantly falling! If it wasn’t moving forward at tens of thousands of miles an hour it would hit the Earth. It’s moving fast enough to fall around the curvature of the Earth as it falls but, indeed, it’s falling as the Earth’s gravity is pulling it to us.


Otherwise the ship would float out to space. So what is the astronaut doing? She’s falling, too! The astronaut and the space ship are both falling to the Earth at the same rate of speed and so the astronaut feels weightless in space. If you were in an elevator and the cable snapped, you and the elevator would fall to the Earth at the same rate of speed. You’d feel weightless! (Don’t try this at home!)


Either now, or at some point in the future you may ask yourself this question, “How can gravity pull harder (put more force on some things, like bowling balls) and yet accelerate all things equally?” When we get into Newton’s laws in a few lessons, you’ll realize that doesn’t make any sense at all. More force equals more acceleration is basically Newton’s Second law.


Well, I don’t want to take too much time here since this is a little deeper then we need to go but I do feel some explanation is in order to avoid future confusion. The explanation for this is inertia. When we get to Newton’s First law we will discuss inertia. Inertia is basically how much force is needed to get something to move or stop moving.


Now, let’s get back to gravity and acceleration. Let’s take a look at a bowling ball and a golf ball. Gravity puts more force on the bowling ball than on the golf ball. So the bowling ball should accelerate faster since there’s more force on it. However, the bowling ball is heavier so it is harder to get it moving. Vice versa, the golf ball has less force pulling on it but it’s easier to get moving. Do you see it? The force and inertia thing equal out so that all things accelerate due to gravity at the same rate of speed!


Gravity had to be one of the first scientific discoveries. Whoever the first guy was to drop a rock on his foot, probably realized that things fall down! However, even though we have known about gravity for many years, it still remains one of the most elusive mysteries of science. At this point, nobody knows what makes things move toward a body of mass.


Why did the rock drop toward the Earth and on that guy’s foot? We still don’t know. We know that it does, but we don’t know what causes a gravitational attraction between objects. Gravity is also a very weak force. Compared to magnetic forces and electrostatic forces, the gravitational force is extremely weak. How come? No one knows. A large amount of amazing brain power is being used to discover these mysteries of gravity. Maybe it will be you who figures this out!


Exercises


  1. Of the following objects, which ones are attracted to one another by gravity?
    a) Apple and Banana b) Beagle and Chihuahua c) Earth and You d) All of the above
  2. True or False: Gravity accelerates all things differently
  3.  True or False: Gravity pulls on all things differently
  4.  If I drop a golf ball and a golf cart at the same time from the same height, which hits the ground first?
  5.  There is a monkey hanging on the branch of a tree. A wildlife biologist wants to shoot a tranquilizer dart at the monkey to mark and study him. The biologist very carefully aims directly at the shoulder of the monkey and fires. However, the gun makes a loud enough noise that the monkey gets scared, lets go of the branch and falls directly downward. Does the dart hit where the biologist was aiming, or does it go higher or lower then he aimed? (This, by the way, is an old thought problem.)

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Star Gazing

Sunday September 1, 2013

Telescopes and binoculars are pretty useless unless you know where to point them. I am going to show you some standard constellations and how to find them in the night sky, so you’ll never be lost again in the ocean of stars overhead. We’re going to learn how to go star gazing using planetarium software, and how to customize to your location in the world so you know what you’re looking at when you look up into the sky tonight!
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Materials: You’ll need to download and install Stellarium Planetarium Software before watching the video below. If you need a paper planetarium, try downloading this star wheel from Sky & Telescope here or try this simple star wheel here.



Click to download the student worksheet.


You’re about to locate several different celestial objects by first finding them in your planetarium software (or after assembling your star wheel).


UPDATE! There’s a complete STARGAZING set of lessons now available! Go here to find the new STARGAZING LESSONS!


  1. If you haven’t already, customize your planetarium software to your location by entering in your location and elevation.
  2. Now adjust the time so that it’s set to the time you’d like to star gaze tonight. What time will you star gaze tonight? Write this in your science notebook.
  3. For folks in the Northern Hemisphere, find the Big Dipper. For Southern Hemisphere folks, find the Southern Cross (or the Crux, but it really looks like a big kite). These are one of the most recognizable patterns, and easy for beginners to find.
  4. For Northerners, use the Big Dipper to locate Polaris, the North Star. The two stars at the edge of the dipper point straight to the North Star. (Refer to top image.)
  5. For Southerners, use the Southern Cross to find the south pole of the sky (sometimes called the “south pole pit” since there’s no star there at the exact pole point of the southern sky). The longer bar in the cross points almost exactly toward the South Pole. (Refer to bottom image.)
  6. Using the Search option, find the planets that will be visible tonight by typing in their name into the search window. Which ones will be visible for you tonight? Write this in your science notebook.
  7. In Stellarium, click the “Search” icon, then the “Lists” tab, and select “Constellations”. Select two different  constellations you’d like to find tonight that are visible to you, and record information about them on a piece of paper so you have it with you tonight. Include information about how you’ll find it (for example, what is it next to?)
  8. When you’re ready, flip open your science notebook to the page with what you’re planning to look at, grab a a flashlight, pencil, and then go outside to log your observations, just like a real scientist!

Observing Tip: Try to observe when the moon is less than first quarter phase or more than three quarters (meaning that the moon is less than 50% illuminated). You don’t need any fancy viewing equipment, only your science notebook, and if you can do it, bring your planetarium software program with you outside to help you locate the objects. Start small, and find a couple of things on the first night. If you don’t figure it out the first time, try again the next night. I learned the northern sky by learning one new constellation every time I went star gazing, and pretty soon I had a lot of them that I could identify easily.


Note: This isn’t something that’s going to work by osmosis. You will have to go outside, figure out where to look, and find the object. Figure out what you’re looking for, and about where you can expect to find it, and practice and test yourself over and over until you can successfully find it every time. If you’re getting frustrated, it’s time to stop and have a sip of hot cocoa before you try again. This is supposed to be a fun treasure hunt, so make it enjoyable!


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Neptune’s Furnace

Sunday September 1, 2013

We’re going to do a chemistry experiment to simulate the heat generated by the internal core of Neptune by using a substance used for melting snow mixed with baking soda.


Calcium chloride splits into calcium ions and chloride ions when it is mixed with water, and energy is released in the form of heat. The energy released comes from the bond energy of the calcium chloride atoms, and is actually electromagnetic energy. When the calcium ions and chloride ions are floating around in the warm solution, they are free to interact with the rest of the ingredients added, like the sodium bicarbonate, to form carbon dioxide gas and sodium chloride (table salt).


Materials


  • Calcium chloride
  • Sodium bicarbonate (baking soda)
  • Phenol red or red food dye
  • Re-sealable plastic baggie
  • Gallon milk jug container
  • Straight pin
  • Warm water
  • Cold water

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Download Student Worksheet & Exercises


  1. Cut the top off the milk jug just above the handle so you can easily put your experiment in the jug.
  2. Fill your milk jug with cold water most of the way. Leave enough room for you to add the bag without overflowing the water, and make sure you put in very cold water. Set this aside.
  3. Add an inch of warm water to the plastic bag.
  4. Add a couple of drops of red dye to the bag.
  5. If you are using a hot pack, open the hot pack (use scissors) carefully. You don’t want to puncture the water pouch inside. Throw the water pouch away and pour the rest of the contents into a container (this is calcium chloride). You want a couple of tablespoons of calcium chloride in the plastic baggie.
  6. Seal the bag closed and roll the pellets between your fingers.
  7. Use a straight pin and make six holes near the top of the bag, away from the water.
  8. Open the bag and add a couple of tablespoons of sodium bicarbonate (baking soda). Quickly zip up your bag!
  9. Make sure the bag is sealed before inserting it into your cold water jug. Watch carefully for several minutes and record your observations with the next step.
  10. Draw your experiment during step 9. Label all parts of what’s going on with your experiment:

What’s Going On?

We’re simulating the heat generation on Neptune using a chemistry experiment with a hot pack.


Most instant hot packs available in drugstores work on this same principle we’re about to investigate. When the hot pack is needed, the bag is squeezed to cause the water and salt to mix. Depending on the salt used in the pack, energy is either absorbed (cold pack) or given off (hot pack). Ammonium nitrate is the most commonly used salt in cold packs. And calcium chloride is the most commonly used salt in hot packs.


Calcium chloride splits into calcium ions and chloride ions when it is mixed with water, and energy is released in the form of heat. This is the same heat energy you will feel when holding the baggie and rubbing the pellets.


Dissolving calcium chloride is highly exothermic, meaning that it gives off a lot of heat when mixed with water (the water can reach up to 140oF, so watch your hands!). The energy released comes from the bond energy of the calcium chloride atoms, and is actually electromagnetic energy.


When the calcium ions and chloride ions are floating around in the warm solution, they are free to interact with the rest of the ingredients added, like the sodium bicarbonate, to form carbon dioxide gas and sodium chloride (table salt). You can tell there’s carbon dioxide gas inside when the bag puffs up.


As the gas in the bag increases, it puffs out and increases the pressure. This stretches the bag and some of the gas is released out the holes in the top of the bag, bubbling up to the surface of the milk jug. After a while, the warm water will also rise out of the holes due to the temperature difference between the bag and jug and you’ll see red drift up to the top surface of the milk jug. The heat generated by Neptune is deep in the core, and it bubbles up and radiates out to space, just like the warm bag bubbling its contents to the cold water jug. The entire planet is a whirling, swirling, fast-moving ball of gas and ice that move because of temperature and pressure differences.


Neptune is one of the ice giants of our solar system, and the furthest planet from the sun. Because it’s a gas giant, you couldn’t land your spaceship on the surface because it doesn’t have one. You’d continuously fall until the pressure crushed your ship. And then when you got down far enough, you’d be roasted, because Neptune radiates 2.6 times more energy than it gets from the Sun. That’s impressive, especially since it’s so far from the Sun (30.1 AU, or more than 30 times the Earth-Sun distance). The average daily wind speed on Neptune is 1,200 mph. That’s four times faster than the biggest hurricanes on Earth!


Neptune has more mass than Uranus even though it’s smaller than Uranus. The rings around the planet weren’t confirmed until a space probe passed it and sent us back pictures of the blue planet. It’s hard for backyard astronomers to find this planet, since it’s not a naked-eye object. You need a complicated-looking set of star charts or a GPS tracking system coupled with astronomical data to point your scope in the right direction. Even then, all you see is a white-blue looking star.


Although it’s a gas giant, it’s classified as an ice giant, since there are large amounts of methane and ammonia ices in the upper atmosphere, giving the planet its blue color. The largest of 13 moons is Triton (not to be confused with Saturn’s massive moon, Titan), which orbits Neptune in the opposite direction from the planet’s rotation and also up at an incline from the planet’s equator.


Exercises


  1. What happens when the chemicals come in contact with each other?
  2. What did you notice when you sealed the bag closed and rolled the pellets between your fingers?
  3. What happened when the solution is placed in the cold water jug?
  4. What does this experiment have to do with Neptune? Why did we use the baking soda at all?

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Planetarium and Star Show

Sunday September 1, 2013

Greetings and welcome to the study of astronomy! This first lesson is simply to get you excited and interested in astronomy so you can decide what it is that you want to learn about astronomy later on.


We’re going to cover a lot in this presentation, including: the Sun, an average star, is the central and largest body in the solar system and is composed primarily of hydrogen and helium.


The solar system includes the Earth, Moon, Sun, seven other planets and their satellites (moons) and smaller objects such as asteroids and comets. The structure and composition of the universe can be learned from the study of stars and galaxies. Galaxies are clusters of billions of stars, and may have different shapes. The Sun is one of many stars in our own Milky Way galaxy. Stars may differ in size, temperature, and color.


Materials


  • Popcorn
  • Pencil

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Download Student Worksheet & Exercises


Before watching the video, print out your worksheet so you can jot things down as you listen. Then grab your pencil (and a handful of popcorn) and fill it in as you go along, or simply enjoy the show and fill it out at the end.


What’s Going On?

Astrophysics is the branch of astronomy that deals with the physics of the universe. Astronomers study celestial objects (things like stars, planets, moons, asteroids, comets, galaxies, and so forth) that exist outside Earth’s atmosphere. It’s the one field of study that combines the most science, engineering and technology areas in one fell swoop. Astronomy is also one of the oldest sciences on the planet.


Early astronomers tracked the movement of the stars so accurately that in most cases, we’ve only made minor adjustments to their data. Although Galileo wasn’t the first person to look through a telescope, he was the first to point it at the stars. Originally, astronomy was used for celestial navigation and was involved with the making of calendars, but nowadays it’s mostly classified in the field called astrophysics.


Questions to Answer:


  1. What happened to Pluto?
  2.  How does the Sun make energy?
  3.  Which planet is your favorite and why?
  4.  How many moons around Jupiter and Saturn can you see with binoculars?
  5.  What’s the difference between a galaxy and a black hole?
  6.  How many Earths can fit inside the Sun?

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Song of the Sun

Sunday September 1, 2013

Helioseismology is the study of wave oscillations in the Sun. By studying the waves, scientists can tell what’s going on inside the Sun. It’s like studying earthquakes to learn what’s going on inside the earth. The Sun is filled with sound, and studying these sound waves is currently the only way scientists can tell what’s going on inside, since the light we see from the Sun is just from the upper surface.


Molecules are vibrating back and forth at fairly high rates of speed, creating waves. Energy moves from place to place by waves. Sound energy moves by longitudinal waves (the waves that are like a slinky). The molecules vibrate back and forth, crashing into the molecules next to them, causing them to vibrate, and so on and so forth. All sounds come from vibrations.


Materials


  • Musical instruments: triangles, glass bottles that can be blown across, metal forks, tuning forks, recorders, jaw harps, harmonicas, etc. Whatever you have will work fine.

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Download Student Worksheet & Exercises


  1. Your teacher will pull out a bin of musical instruments of various types.
  2. Assign one student to be the noisemaker. The rest will listen with their eyes closed and record their observations.
  3. Everyone shuts their eyes except for the noise maker.
  4. The noisemaker selects an instrument and plays it once. Everyone else listens.
  5. The noisemaker selects another instrument and plays it once. Everyone listens.
  6. The noisemaker selects a third instrument and plays it once. Everyone listens.
  7. The noisemaker selects one of the three instruments and plays it as it moves. For example, if you’re playing the triangle, you can hit it and spin it. Or hit it as you are walking past the closed-eye listeners. Sound changes when the object is moving, so make the sound they hear appear to be different somehow.
  8. The noisemaker puts the instruments back and everyone opens their eyes and records their data in the table.
  9. Switch roles and find a new noisemaker for the next trial. Repeat steps 2-8.

What’s Going On?

The Sun is like the biggest musical instrument you’ve ever seen. A piano has 88 keys, which means you can play 88 different musical notes. The Sun has 10 million.


To play a guitar, you pluck one of the six strings. To play the piano, you hit a key and sound comes out. To play the flute, you blow across a hole. Drums require smacking things together. So how do you play the Sun?


Molecules are vibrating back and forth at fairly high rates of speed, creating waves. Energy moves from place to place by waves. Sound energy moves by longitudinal waves (the waves that are like a slinky). The molecules vibrate back and forth, crashing into the molecules next to them, causing them to vibrate, and so on and so forth. All sounds come from vibrations.


Waves are the way energy moves from place to place. Sound moves from a mouth to an ear by waves. Light moves from a light bulb to a book page to your eyes by waves. Waves are everywhere. As you sit there reading this, you are surrounded by radio waves, television waves, cell phone waves, light waves, sound waves and more. (If you happen to be reading this in a boat or a bathtub, you’re surrounded by water waves as well.) There are waves everywhere!


Do you remember where all waves come from? Vibrating particles. Waves come from vibrating particles and are made up of vibrating particles.


Here’s rule one when it comes to waves….the waves move, the particles don’t. The wave moves from place to place. The wave carries the energy from place to place. The particles however, stay put. Here are a couple of examples to keep in mind.


If you’ve ever seen a crowd of people do the “wave” in the stands of a sporting event you may have noticed that the people only “vibrated” up and down. They did not move along the wave. The wave, however, moved through the stands.


Another example would be a duck floating on a wavy lake. The duck is moving up and down (vibrating) just like the water particles but he is not moving with the waves. The waves move, but the particles don’t. When I talk to you, the vibrating air molecules that made the sound in my mouth do not travel across the room into your ears. (Which is especially handy if I’ve just eaten an onion sandwich!) The energy from my mouth is moved, by waves, across the room.


Convection starts the waves moving. You’ve seen convection when a hot pot of water bubbles up. You can even hear it when it starts to boil if you listen carefully. Just below the surface of the Sun, the energy that started deep in the core has bubbled up to the surface to make gigantic bubbles emerge that are bigger than the state of Alaska. It’s also a noisy process, and the sound waves stay trapped beneath the surface, making waves appear on the surface of the Sun. This makes the Sun’s surface look like it’s moving up and down.


Scientists use special cameras to watch the surface of the Sun wiggle and move, and they look for patterns so they can determine what’s going on down inside the Sun. Since the sound is inside the Sun under the part we can see, we use sound to discover what’s inside the Sun.


Have you ever heard the Sun? The video is an actual recording of the song of the Sun.


If you’ve ever been inside an unfurnished room, you’ve heard echoes indoors. Sound bounces all around the room, just like it does inside the surface of the Sun.


Can sound waves travel through space? No. Sound requires a medium to travel through, since it travels by vibrating molecules, and there aren’t enough molecules in space to do this with (there are a couple random ones floating around here and there, but way too far apart to be useful for sound waves).


If you have a slinky, take it out and stretch it out to its full length on the table or the ground, asking someone to help you hold one end. Now move the slinky quickly to the left and back again, and watch the wave travel down the length and return. Now move your end quickly up and then back down the table, making a longitudinal wave. When this wave finishes, take your end and shove it quickly toward your helper, then pull back again to make a compression wave. Point out to the student how when the wave returns, it’s an echo. That’s what happens inside the Sun when the sound waves hit the surface of the Sun. They don’t go through the surface, but get trapped beneath it as they echo off the inside surface of the Sun.


Exercises


  1.  What did you notice that is different about the sounds you heard?
  2.  How can you tell that two sounds are different that came from the same instrument? (Movement causes sound waves to sound different.)
  3. What did you notice about your guesses? What kind of instruments were you more correct about?

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Jupiter’s Jolts

Sunday September 1, 2013

Jupiter not only has the biggest lightning bolts we’ve ever detected, it also shocks its moons with a charge of 3 million amps every time they pass through certain hotspots. Some of these bolts are cause by the friction of fast-moving clouds. Today you get to make your own sparks and simulate Jupiter’s turbulent storms.


Electrons are too small for us to see with our eyes, but there are other ways to detect something’s going on. The proton has a positive charge, and the electron has a negative charge. Like charges repel and opposite charges attract.


Materials


  • Foam plate
  • Foam cup
  • Wool cloth or sweater
  • Plastic baggie
  • Aluminum pie pan
  • Aluminum foil
  • Film canister or M&M container
  • Nail (needs to be a little longer than the film canister)
  • Hot glue gun or tape
  • Water

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Download Student Worksheet & Exercises


  1. Lay the aluminum pie pan in front of you, right-side up.
  2. Glue the foam cup to the middle of the inside of the pan.
  3. Lay the plate on the table, upside down. Place the pie pan (don’t glue it!) on top of the plate, back-to-back. Set aside.
  4. Insert the nail through the middle of the film canister lid. Wrap the bottom of the film canister with aluminum foil. Tape the foil into place.
  5. Fill the canister nearly full of water.
  6. Snap on the lid, making sure that the nail touches the water.
  7. Rub the foam plate with the wool for at least a minute to really charge it up. Place the plate upside down carefully on the table.
  8. Put the pie pan back on top of the foam plate. The plate has taken on the charge from the foam plate.
  9. Touch the pie pan with a finger… did you feel anything?
  10. Use the cup as a handle and lift the pie pan up.
  11. Touch the pan with your finger, and you should feel and see a spark (turn down the lights to make the room dark).
  12. Charge the foam plate again and set the pie pan back on top to charge it up. (Make sure you’re lifting the pie pan only by the foam cup, or you’ll discharge it accidentally.)
  13. Hold the film canister by the aluminum foil and touch the charged pie pan to the nail.
  14. Rub the foam plate with the wool again to charge it up. Set the pie pan on the foam plate to charge the pan. Now lift the pie pan and touch the pan to the nail. Do this a couple of times to really get a good charge in the film canister.
  15. Discharge the film canister by touching the foil with one finger and the nail with the other. Did you see a spark?
  16. The wool gives the plate a negative charge. You can use a plastic bag instead of the wool to give the foam plate a positive charge.

What’s Going On?

If you rub a balloon on your head, the balloon becomes filled up with extra electrons, and now has a negative charge. Try the following experiment to create a temporary charge on a wall: Bring the balloon close to the wall until it sticks.


Opposite charges attract right? So, is the entire wall now an opposite charge from the balloon? No. In fact, the wall is not charged at all. It is neutral. So why did the balloon stick to it?


The balloon is negatively charged. It created a temporary positive charge when it got close to the wall. As the balloon gets closer to the wall, it repels the electrons in the wall. The negatively charged electrons in the wall are repelled from the negatively charged electrons in the balloon.


Since the electrons are repelled, what is left behind? Positive charges. The section of wall that has had its electrons repelled is now left positively charged. The negatively charged balloon will now “stick” to the positively charged wall. The wall is temporarily charged because once you move the balloon away, the electrons will go back to where they were and there will no longer be a charge on that part of the wall.


This is why plastic wrap, Styrofoam packing popcorn, and socks right out of the dryer stick to things. All those things have charges and can create temporary charges on things they get close to.


If you rub a balloon all over your hair, the Triboelectric Effect causes the electrons to move from your head to the balloon. But why don’t the electrons go from the balloon to your head? The direction of electron transfer has to do with the properties of the material itself. And the balloon-hair combination isn’t the only game in town.


Electrons move differently depending on the materials that are rubbed together. A balloon takes on a negative charge when rubbed on hair. Today, the kids are going to find when a foam plate is rubbed with wool, the plate takes on electrons and creates a negative charge on the plate. To give the plate a positive charge, kids can rub it with a plastic bag.


The Triboelectric Series is a list that ranks different materials according to how they lose or gain electrons. A rubber rod rubbed with wool produces a negative charge on the rod, however an acrylic rod rubbed with silk creates a positive charge on the rod. A foam plate often has a positive charge when you slide one off the stack, but if you rub it with wool it will build up a negative charge.


Near the top of the list are materials that take on a positive charge, such as air, human skin, glass, rabbit fur, human hair, wool, silk, and aluminum. Near the bottom of the list are materials that take on a negative charge, such as amber, rubber balloons, copper, brass, gold, cellophane tape, Teflon, and silicone rubber. Scientists developed this list by doing a series of experiments, very similar to the ones we’re about to do.


Exercises


  1. What happens if you hold the nail and charge the aluminum foil?
  2. Can you see electrons? Why or why not?

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Moons of Jupiter

Sunday September 1, 2013

On a clear night when Jupiter is up, you’ll be able to view the four moons of Jupiter (Europa, Ganymede, Io, and Callisto) and the largest moon of Saturn (Titan) with only a pair of binoculars. The question is: Which moon is which? This lab will let you in on the secret to figuring it out.


You get to learn how to locate a planet in the sky with a pair of binoculars, and also be able to tell which moon is which in the view.


Materials


  • Printout of corkscrew graph
  • Pencil
  • Binoculars (optional)

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Download Student Worksheet & Exercises


  1. Look at your corkscrew satellite graph. These are common among astronomers for both Saturn and Jupiter. Notice how Saturn has a lot more wavy lines than Jupiter. We’re going to focus on Jupiter for the first part of this lab. Jupiter’s graph is the one on the left with Ganymede as one of the moons.
  2. The wavy lines represent four of Jupiter’s biggest moons: Ganymede, Callisto, Europa, and Io. The central two lines for a band is the width of Jupiter itself. If you see any gaps in the wavy lines, those are times when the moon is behind Jupiter. Each bar across that corresponds to a number is an entire day. The width of the column represents how far away each moon is from Jupiter. Notice at the top it says East and West.
  3. Draw a circle that represents Jupiter.
  4. Notice the largest waves are made by Callisto. Who makes the smallest waves? (Io.)
  5. Look at Dec 4th. Which moons are on which side of Jupiter? (Ganymede is the furthest east, and Io is closer to the planet, still on the east side. On the west, Europa is closer to Jupiter than Callisto.)

What’s Going On?

Jupiter’s Rings and Moons


Jupiter’s moons are threadlike when compared with Saturn’s. Also, unlike Saturn’s rings, Jupiter’s rings come from ash spewed out from the active volcanoes of its moons. Since Jupiter is so large, its gravity likes to catch things. When a volcano shoots its ash-snow up, Jupiter grabs it and swirls it in on itself. The moons are constantly replenishing the rings, which is why they are so much smaller than Saturn’s and much harder to detect (you won’t see them with binoculars or a backyard telescope).


moons-jupiterIf you’re doing the binocular portion of this lab in the evening, the numbers on binoculars refer to the magnification and the lens at the end. For example, 7×50 means you’re viewing the sky at 7X, and the lenses are at 50mm. Most people can easily hold up to 10x50s before their arms get tired. Remember, you’re looking up, not out or down as in normal terrestrial daytime viewing.


Saturn’s Rings and Moons


Galileo Galilei was the first to point a telescope at the sky, and the first to glance at the rings of Saturn in 1610. In the 1980s, the Voyager 1 and Voyager 2 spacecraft flew by, giving us our first real images of the rings of Saturn. Some of the biggest mysteries in our solar system are: What are the rings made up of, and why?


The Cassini-Huygens Mission answered the first question: The rings are made of billions of particles ranging from dust-sized icy grains to a couple of mountain-sized chunks. Actually, Saturn’s rings are an optical illusion. They are not solid, but rather a blizzard of water-ice particles mixed with dust and rock fragments, and each piece orbits Saturn like a little a moon. These billions of particles race around Saturn in tracks, and are herded into position by moons that also orbit within the rings (“shepherd” moons). Shepherd moon Pan orbits in the Encke gap, Daphnis orbits in the Keeler gap, Atlas orbits in the A ring, Prometheus in the F ring, and Pandora in the F ring. These moons keep the gaps open with their gravity.


The second question is harder to answer, but the latest news is that the rings are pieces of comets, asteroids or shattered moons that broke apart before they ever reached Saturn. Although each ring orbits at a different speed around the planet, the Cassini spacecraft had to slow down to 75,000 mph before it dropped into the rings to orbit around the planet.


While the rings are wide enough to see with a backyard telescope, the main rings (A, B and C) are paper-thin, only 10 meters (33 feet) thick.


Uranus and Neptune are called ice giants because of the amounts of ice in their atmospheres. Their atmospheres are also made of mostly hydrogen and helium.


Cassini found that a great plume of icy material blasting from the moon Enceladus is a major source of material for the expansive E ring. Additionally, Cassini has found that most of the planet’s small, inner moons appear to orbit within partial or complete rings formed from particles blasted off their surfaces by impacts of micrometeoroids.


Exercises


  1. Find a date that has all four moons on one side of Jupiter.
  2.  When is Callisto in front of Jupiter and Io behind Jupiter at the same time?
  3. Are the images you’ve drawn in the table what you’d expect to see in binoculars, or are they upside down, mirrored, or inverted?

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Star Charting

Sunday September 1, 2013

If you want to get from New York to Los Angeles by car, you’d pull out a map. If you want to find the nearest gas station, you’d pull out a smaller map. What if you wanted to find our nearest neighbor outside our solar system? A star chart is a map of the night sky, divided into smaller parts (grids) so you don’t get too overwhelmed. Astronomers use these star charts to locate stars, planets, moons, comets, asteroids, clusters, groups, binary stars, black holes, pulsars, galaxies, planetary nebulae, supernovae, quasars, and more wild things in the intergalactic zoo.


How to find two constellations in the sky tonight, and how to get those constellations down on paper with some degree of accuracy.


Materials


  • Dark, cloud-free night
  • Two friends
  • String
  • Rocks
  • Pencil

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Download Student Worksheet & Exercises


  1. Tape your string to the pencil.
  2. Loosely wrap the string around your finger several times so that the tip of the pencil is about an inch above the ground.
  3. Find a constellation. Point to a star in the constellation.
  4. Have a second person place a rock under the pencil tip.
  5. When they’ve placed the rock in position, point to another star.
  6. Have a second person place a rock under the pencil tip again.
  7. Repeat this process until all the stars have rocks under their positions.
  8. You should see a small version of the constellation on your paper.

What’s Going On?

People have been charting stars since long before paper was invented. In fact, we’ve found star charts on rocks, inside buildings, and even on ivory tusks. Celestial cartography is the science of mapping the stars, galaxies, and astronomical objects on a celestial sphere.


Celestial navigation (astronavigation) made it possible for sailors to cross oceans by sighting the Sun, moon, planets, or one of the 57 pre-selected navigational stars along with the visible horizon.


Watch the video that shows how the stars appear to move differently, depending on which part of the Earth you’re viewing from. What’s the difference between living on the equator or in Antarctica (explained in video)?


The first thing to star chart is the Big Dipper, or other easy-to-find constellation (alternates: Cassiopeia for northern hemisphere or the Southern Cross for the southern hemisphere). The Big Dipper is always visible in the northern hemisphere all year long, so this makes for a good target.


Use glow–in-the-dark stars instead of rocks, and charge them with a quick flash from a camera (or a flashlight). Keep your hand as still as you can while the second person lines the rock into position. You can also unroll a large sheet of (butcher or craft) paper and use markers to create a more permanent star chart.


Exercises:


  1. If you have constellations on your class ceiling, chart them on a separate page marking the positions of the rocks with X’s.
  2. Tonight, find two constellations that you will chart. Bring them with you tomorrow using the technique outlined above in Experiment.

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Cosmic Ray Detector

Thursday August 1, 2013

When high energy radiation strikes the Earth from space, it’s called cosmic rays. To be accurate, a cosmic ray is not like a ray of sunshine, but rather is a super-fast particle slinging through space. Think of throwing a grain of sand at a 100 mph… and that’s what we call a ‘cosmic ray’. Build your own electroscope with this video!


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Materials:


  • Clean glass jar with a lid
  • Wire coat hanger and sand paper
  • Aluminum foil
  • Vice grips or a hacksaw
  • Scissors
  • Balloon or other object to create a static charge
  • Hot glue gun (optional)


 


Download Student Worksheet & Exercises


Troubleshooting: This device is also known as an electroscope, and its job is to detect static charges, whether positive or negative.  The easiest way to make sure your electroscope is working is to rub your head with a balloon and bring it near the foil ball on top – the foil “leaves” inside the jar should spread apart into a V-shape.


Exercises


  1. How does this detector work?
  2. Do all particles leave the same trail?
  3. What happens when the magnet is brought close to the jar?

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Telling Time by the Stars

Tuesday June 25, 2013

The stars rise and set just like our sun, and for people in the northern hemisphere, the Big Dipper circles the north star Polaris once every 24 hours. Would you like to learn how to tell time by the stars?


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From the northern hemisphere, the Big Dipper is above the horizon for most of the year. In the spring time (especially in March), it’s fun and easy to learn how to tell time by the stars!


First, go outside after sunset and find the Big Dipper. Use a compass if you need to to find NORTH, then tilt your head back and look up from the horizon for seven bright stars.


Draw a line through two bowl stars (furthest from the handle) and extend that line so it hits the north “pole” star Polaris.


The “sky clock” is a 24-hour clock, not a 12-our clock like the one in your house. Polaris is the center of the clock, and the hour hand is the line you drew from the Big Dipper to Polaris.



Now use this simple formula: The current TIME = the clock reading MINUS twice the number of months after March 6. (You can use March 1 to make it easier to figure out.) Imagine we’re in March right now, so that “number of months past March” is ZERO. (See why it’s easy in March?) So go look up at the sky clock and read what time it is!


Notice how we read the sky clock COUNTERCLOCKWISE. This is opposite of the clock in your kitchen.


Let’s take another example. Suppose it’s Dec. 1st.


Dec 1 is close to Dec 6, so let’s figure about 9 months (to be exact, it would be 8.75 months, but let’s make it easy to calculate this time through). The night sky looks like the second image (without the clock superimposed over it). Can you tell me what time it is?


ANSWER:
The clock reads 2PM. The correction is 2 x 9 = 18. That is 18 hours we will need to SUBTRACT from 2PM.


So the time I read on the clock is about 2am (you could say 1:30am, but I am trying to make it easier here).


Now subtract 12 hours to make that PM into AM.


Now we only need to subtract 6 more hours.


Subtract 6 hours from 2AM to get 8PM!


The more you practice this, the easier it will be!
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Phases of the Moon

Monday June 24, 2013

The Moon appears to change in the sky. One moment it’s a big white circle, and next week it’s shaped like a sideways bike helmet. There’s even a day where it disappears altogether. So what gives?


The Sun illuminates half of the Moon all the time. Imagine shining a flashlight on a beach ball. The half that faces the light is lit up. There’s no light on the far side, right? For the Moon, which half is lit up depends on the rotation of the Moon. And which part of the illuminated side we can see depends on where we are when looking at the Moon. Sound complicated? This lab will straighten everything out so it makes sense.


Materials


  • ball
  • flashlight

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This first video will show you how the moon changes it’s appearance over the course of its cycle:




This video will show you how to demonstrate why the moon changes it’s appearance over the course of its cycle:



 
Download Student Worksheet & Exercises


  1. This lab works best if your room is very dark. Button down those shades and make it as dark as you can.
  2. Assign one person to be the Sun and hand them the flashlight. Stay standing up about four feet away from the group. The Sun doesn’t move at all for this activity.
  3. Assign one person to be the Moon and hand them the ball. Stay standing up, as you’ll be circling the Earth.
  4. The rest of the people are the Earth, and they stand or sit right the middle (so they don’t get a flashlight in their eyes as the Moon orbits).
  5. Start with a new Moon. Shine the flashlight above the heads of the Earth. Move the Moon (ball) into position so that the ball blocks all the light from the flashlight. Ask the Earth kids how much light they can see on their side of the Moon (should be none). Which phase of the Moon is this?
  6. Now the Moon moves around to the opposite side of the Earth so that the Earth kids can see the entire half of the ball lit up by the flashlight. Ask the Earth kids how much light they can see on their side of the Moon (should be half the ball). Which phase of the Moon is this?
  7. Now find the positions for first quarter. Where does the Moon need to stand so that the Earth kids can see the first quarter Moon?
  8. Continue around in a complete circle and fill out the diagram. Color in the circles to indicate the dark half of the Moon. For example, the new Moon should be completely darkened.
  9. Now it’s time to investigate why Venus and Mercury have phases. Put the Sun in the center and assign a student to be Venus. Venus gets the ball.
  10. Venus should be walking slowly around the Sun. The Sun is going to have to rotate to always face Venus, since the Sun normally gives off light in every direction.
  11. The Earth kids need to move further out from the Sun than Venus, so they will be watching Venus orbit the Sun from a distance of a couple of feet.
  12. Earth kids: What do you notice about how the Sun lights up Venus from your point of view? Is there a time when you get to see Venus completely illuminated, and other times when it’s completely dark?
  13. Draw a diagram of what’s going on, labeling Venus’s full phase, new phase, half phases, crescent, and gibbous phases. Label the Sun, Earth, and all eight phases of Venus.

Reading


The Sun illuminates half of the Moon all the time. Imagine shining a flashlight on a beach ball. The half that faces the light is lit up. There’s no light on the far side, right? So for the Moon, which half is lit up depends on the rotation of the Moon. And which part of the illuminated side we can see depends on where we are when looking at the Moon. Sound complicated? This lab will straighten everything out so it makes sense.


One question you’ll hear is: Why don’t we have eclipses every month when there’s a new Moon? The next lesson is all about eclipses, but you can quickly answer their questions by reminding them that the Moon’s orbit around the Earth is not in the same plane as the Earth’s orbit around the Sun (called the ecliptic). It’s actually off by about 5o. In fact, only twice per month does the Moon pass through the ecliptic.


The lunar cycle is approximately 28 days. To be exact, it takes on average 29.53 days (29 days, 12 hours, 44 minutes) between two full moons.  The average calendar month is 1/12 of a year, which is 30.44 days. Since the Moon’s phases repeat every 29.53 days, they don’t quite match up. That’s why on Moon phase calendars, you’ll see a skipped day to account for the mismatch.


A second full Moon in the same month is called a blue Moon. It’s also a blue Moon if it’s the third full Moon out of four in a three-month season, which happens once every two or three years.


The Moon isn’t the only object that has phases. Mercury and Venus undergo phases because they are closer to the Sun than the Earth. If we lived on Mars, then the Earth would also have phases.


Exercises


  1. Does the sun always light up half the Moon?
  2. How many phases does the Moon have?
  3. What is it called when the Moon appears to grow?
  4. What is it called when you see more light than dark on the Moon?
  5. How long does it take for a complete lunar cycle?

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Does it rain on the sun?

Saturday March 2, 2013

Does it rain on the Sun? The answer to this is yes, however, it is not water that falls but very hot plasma. On July 19, 2012, there was an eruption on the Sun that produced a massive burst of solar wind and magnetic fields and released into Space. This eruption also produced a powerful solar flare. After that, a phenomenon known as coronal rain occurred. Corona Rain occurs occurs when hot plasma in the corona cools and condenses in strong magnetic fields, usually associated with regions that produce solar flares. The plasma condenses and slowly falls back to the solar surface.


The electrons, protons and ions in the rain is forced to move along the magnetic loops of the Sun’s surface. As a result, this bright flare highlights matter glowing at a temperature of about 50,000 Kelvin. The entire coronal rain lasted about 10 hours.



Video Credit : http://apod.nasa.gov/apod/ap130226.html


Flying Over the Earth at Night

Friday August 24, 2012

Many wonders are visible when flying over the Earth at night, especially if you are an astronaut on the International Space Station (ISS)! Passing below are white clouds, orange city lights, lightning flashes in thunderstorms, and dark blue seas. On the horizon is the golden haze of Earth’s thin atmosphere, frequently decorated by dancing auroras as the video progresses. The green parts of auroras typically remain below the space station, but the station flies right through the red and purple auroral peaks. You’ll also see solar panels of the ISS around the frame edges. The wave of approaching brightness at the end of each sequence is just the dawn of the sunlit half of Earth, a dawn that occurs every 90 minutes, as the ISS travels at 5 miles per second to keep from crashing into the earth.




Video Credit: Gateway to Astronaut Photography, NASA


Curiosity Rover Successfully Lands on Mars on August 5th!

Tuesday August 7, 2012

This is the stuff of dreams, imagination, creativity and innovation.This is especially cool for parents to have their children witness something “out of this world” live as it happens. This is American science education at its absolute finest.


NASA’s Jet Propulsion Laboratory (JPL) has done it again, BIG TIME!


In normal fashion for JPL in Pasadena, this was no normal, everyday kind of landing, as Curiosity will blast into the Martian atmosphere at 13,000 miles per hour and in a death-defying “Seven Minutes of Terror” come to a soft landing on Mars. Fingers and toes were crossed. And, due to its heavy weight, it will not land like Spirit and Opportunity did about 8 years ago landing in cushioned, inflated air bags that looks like giant raspberries. Curiosity was lowered to the surface under a rocket-powered sky-crane, never before attempted by any spacecraft. Mars Science Laboratory Curiosity is the most sophisticated and complex robotic spacecraft ever built.


Even now that this event has happened, you can witness this history-making event through these special  NASA TV video along with millions of people around the world.


Curiosity was launched on an Atlas V rocket from Cape Canaveral on November 26, 2011:



Some folks may have heard that there was a problem anticipated with the transmission of the landing telemetry (radio signal), possibly taking hours before we would know what happened during the landing. That problem was with America’s Mars Odyssey spacecraft orbiting Mars (along with America’s Mars Reconnaissance Orbiter and Europe’s Mars Express Orbiter). A “reaction wheel” that helps control Mars Odyssey’s orbital path location had problems, that could have impacted its ability to receive and relay the telemetry as it happens. The week before landing, JPL engineers successfully corrected the issue, putting Mars Odyssey back on course to directly receive the landing telemetry and beam it back to Earth as it is happening.



Newsflash! Curiosity has successfully landed on the surface of Mars!


Bear in mind that the transmission time from Mars to Earth will be about 14 minutes at the speed of light, so Curiosity will have experienced the Seven Minutes of Terror and landed before we get the signals from Mars. Hold your breath and wish Curiosity the best as you watch these videos!



Here are some of the first images:

More images are being posted by NASA here: Mars Science Laboratory Image Gallery


How to Find New Planets around Distant Stars

Monday November 7, 2011

How do astronomers find planets around distant stars? If you look at a star through binoculars or a telescope, you’ll quickly notice how bright the star is, and how difficult it is to see anything other than the star, especially a small planet that doesn’t generate any light of its own!


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Astronomers look for a shift, or wobble, of the star as it gets gravitationally ‘yanked’ around by the orbiting planets. By measuring this wobble, astronomers can estimate the size and distance of larger orbiting objects.


Here’s how you can show this effect to other folks:



 
Download Student Worksheet & Exercises


Exercises


  1. For homework tonight, find out how many extrasolar planets scientists have detected so far.
  2. Also for homework, find out the names (they will probably be a string of numbers and letters together) of the 3 most recent extrasolar planet discoveries.

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What are Aurorae?

Saturday October 22, 2011

Aurora, or ‘northern lights’, is the natural light display in the sky in northern regions like Canada, Alaska, and northern Eurpoean countries that have had people puzzled for centuries as to what exactly they were, and how the light displays were made. Here’s a rare view of the aurorae taken from the International Space Station:



Auroras (or aurorae) happen about 50 miles up, when solar wind hits particles in the Earth’s atmosphere. When charged particles from the solar wind hit the Earth’s magnetosphere (a magnetic field that extends far beyond the Earth’s surface and protects us from solar wind), they are funneled by the Earth’s magnetic field. When these highly charged particles from the sun hit a molecule in our atmosphere, they give off a photon. The green and brownish-red colors come from oxygen and the blue and red are from nitrogen.


In northern latitudes, the aurora borealis was named after the Roman goddess of dawn (Aurora) and the Greek name for the north wind (Boreas). In the south, the aurora australis (or the southern lights) appear anytime the northern lights are visible. This effect is also seen on other planets like Jupiter and Saturn.


Simple Microscope & Telescope

Wednesday September 1, 2010

Did you know you can create a compound microscope and a refractor telescope using the same materials? It’s all in how you use them to bend the light. These two experiments cover the fundamental basics of how two double-convex lenses can be used to make objects appear larger when right up close or farther away.


Things like lenses and mirrors can bend and bounce light to make interesting things, like compound microscopes and reflector telescopes. Telescopes magnify the appearance of some distant objects in the sky, including the moon and the planets. The number of stars that can be seen through telescopes is dramatically greater than can be seen by the unaided eye.


Materials


  • A window
  • Dollar bill
  • Penny
  • Two hand-held magnifying lenses
  • Ruler

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Download Student Worksheet & Exercises


  1. Place a penny on the table.
  2. Hold one magnifier above the penny and look through it.
  3. Bring the second magnifying lens above the first so now you’re looking through both. Move the second lens closer and/or further from the penny until the penny comes into sharp focus. You’ve just made a compound microscope.
  4. Who’s inside the building on an older penny?
  5. Try finding the spider/owl on the dollar bill. (Hint: It’s in a corner next to the “1”.)
  6. Keeping the distance between the magnifiers about the same, slowly lift up the magnifiers until you’re now looking through both to a window.
  7. Adjust the distance until your image comes into sharp (and upside-down) focus. You’ve just made a refractor telescope, just like Galileo used 400 years ago.
  8. Find eight different items to look at through your magnifiers. Make four of them up-close so you use the magnifiers as a microscope, and four of them far-away objects so you use the magnifiers like a telescope. Complete the data table.

What’s Going On?

What I like best about this activity is how easily we can break down the basic ideas of something that seems much more complex and intimidating, like a telescope or microscope, in a way that kids really understand.


When a beam of light hits a different substance (like a window pane or a lens), the speed at which the light travels changes. (Sound waves do this, too!) In some cases, this change turns into a change in the direction of the beam.



For example, if you stick a pencil is a glass of water and look through the side of the glass, you’ll notice that the pencil appears shifted. The speed of light is slower in the water (140,000 miles per second) than in the air (186,282 miles per second). This is called optical density, and the result is bent light beams and broken pencils.


You’ll notice that the pencil doesn’t always appear broken. Depending on where your eyeballs are, you can see an intact or broken pencil. When light enters a new substance (like going from air to water) perpendicular to the surface (looking straight on), refractions do not occur.


However, if you look at the glass at an angle, then depending on your sight angle, you’ll see a different amount of shift in the pencil. Where do you need to look to see the greatest shift in the two halves of the pencil?


Why does the pencil appear bent? Is it always bent? Does the temperature of the water affect how bent the pencil looks? What if you put two pencils in there?


Depending on if the light is going from a lighter to an optically denser material (or vice versa), it will bend different amounts. Glass is optically denser than water, which is denser than air.


Not only can you change the shape of objects by bending light (broken pencil or whole?), but you can also change the size. Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes.


Exercises


  1. Can light change speeds?
  2. Can you see ALL light with your eyes?
  3. Give three examples of a light source.
  4. What’s the difference between a microscope and a telescope?
  5. Why is the telescope image upside-down?

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Pinhole Solar Projector

Wednesday June 30, 2010

You might be curious about how to observe the sun safely without losing your eyeballs. There are many different ways to observe the sun without damaging your eyesight. In fact, the quickest and simplest way to do this is to build a super-easy pinhole camera that projects an image of the sun onto an index card for you to view.


CAUTION: DO NOT LOOK AT THE SUN THROUGH ANYTHING WITH LENSES!!


This simple activity requires only these materials:


  • tack
  • 2 index cards (any size)
  • sunlight

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Here’s what you do:



 
Download Student Worksheet & Exercises


With your tack, make a small hole in the center of one of the cards. Stack one card about 12″ above the over and go out into the sun. Adjust the spacing between the cards so a sharp image of the sun is projected onto the lower paper. The sun will be about the size of a pea.


You can experiment with the size of the hole you use to project your image. What happens if your hole is really big? Too small? What if you bend the lower card while viewing? What if you punch two holes? Or three?


Exercises


  1.  How many longitude degrees per day does the sunspot move?
  2.  Do all sunspots move at the same rate?
  3.  Did some of the sunspots change size or shape, appear or disappear?

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Current Positions of Jupiter’s Moons

Wednesday June 30, 2010

Once you’ve looked at Jupiter through your binoculars, you might be wondering which moon is which. Here’s how you can tell the positions of the four moons.


Can’t find Jupiter? Use this star chart to help locate Jupiter in the night sky:  You can try using an interactive Sky Map if you’re at the computer and want to plan out what you’re going to see tonight and familiarize yourself with the night sky ahead of time, or use the paper Sky Map which is the same one I personally use (it’s free) so you can print it out and take outside with you.


Rusty Balloon

Friday January 1, 2010

Mars is coated with iron oxide, which not only covers the surface but is also present in the rocks made by the volcanoes on Mars.


Today you get to perform a chemistry experiment that investigates the different kinds of rust and shows that given the right conditions, anything containing iron will eventually break down and corrode. When iron rusts, it’s actually going through a chemical reaction: Steel (iron) + Water (oxygen) + Air (oxygen) = Rust
Materials


  • Four empty water bottles
  • Four balloons
  • Water
  • Steel wool
  • Vinegar
  • Water
  • Salt

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Download Student Worksheet & Exercises


  1. This lab is best done over two consecutive days. Plan to set up the experiment on the first day, and finish up with the observations on the next.
  2. Line up four empty bottles on the table.
  3. Label your bottles so you know which is which: Water, Water + Salt, Vinegar, Vinegar + Salt
  4. Fill two bottles with water.
  5. Fill two with vinegar.
  6. Add a tablespoon of salt to one of the water bottles.
  7. Add one tablespoon of salt to one of the vinegar bottles.
  8. Stuff a piece of steel wool into each bottle so it comes in contact with the liquid.
  9. Stretch a balloon across the mouth of each bottle.
  10. Let your experiment sit (overnight is best, but you can shorten this a bit if you’re in a hurry).
  11. The trick to getting this one to work is in what you expect to happen. The balloon should get shoved inside the bottle (not expand and inflate!). Check back over the course of a few hours to a few days to watch your progress.
  12. Fill in the data table.

What’s Going On?

Rust is a common name for iron oxide. When metals rust, scientists say that they oxidize, or corrode. Iron reacts with oxygen when water is present. The water can be liquid or the humidity in the air. Other types of rust happen when oxygen is not around, like the combination of iron and chloride. When rebar is used in underwater concrete pillars, the chloride from the salt in the ocean combines with the iron in the rebar and makes a green rust.


Mars has a solid core that is mostly iron and sulfur, and a soft pastel-like mantle of silicates (there are no tectonic plates). The crust has basalt and iron oxide. The iron is in the rocks and volcanoes of Mars, and Mars appears to be covered in rust.


When iron rusts, it’s actually going through a chemical reaction:
Steel (iron) + Water (oxygen) + Air (oxygen) = Rust


There are many different kinds of rust. Stainless steel has a protective coating called chromium (III) oxide so it doesn’t rust easily.


Aluminum, on the other hand, takes a long time to corrode because it’s already corroded — that is, as soon as aluminum is exposed to oxygen, it immediately forms a coating of aluminum oxide, which protects the remaining aluminum from further corrosion.


An easy way to remove rust from steel surfaces is to rub the steel with aluminum foil dipped in water. The aluminum transfers oxygen atoms from the iron to the aluminum, forming aluminum oxide, which is a metal polishing compound. And since the foil is softer than steel, it won’t scratch.


Exercises


  1. Why did one balloon get larger than the rest?
  2. Which had the highest pressure difference? Why?

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Exercises for Astronomy

Sunday December 13, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.
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  1. If a mad scientist pointed his alpha particle gun straight at you, what would be your best defense?
  2. Did Pluto get smacked out of existence, or is it still there? What other ‘planet’ did this happen to?
  3. How accurate is the main idea in the 2007 movie “Sunshine”, where the mission was to reignite the sun?
  4. How do you make a black hole?
  5. How can you detect a black hole?
  6. What happens if your car zooms at nearly the speed of light and turn on your headlights?
  7. What’s your favorite part about Jupiter?
  8. Which planet is NOW your favorite (after listening to the astronomy teleclass)?
  9. What happened to the stars?
  10. Which stars don’t twinkle?
  11. How many moons can you see with binoculars?

Need answers?


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Answers to Astronomy Exercises

Sunday December 13, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.


Answers:
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  1. Hold up a sheet of paper between you and the gun.
  2. Pluto was once considered one of the planets, but in recent years was demoted to ‘dwarf planet’ status and is now part of the Kuiper Belt Objects. Ceres underwent the same sort of thing in the 1800s, and now belongs to the asteroid belt between Mars and Jupiter.
  3. The sun is not on fire, like a candle. You can’t blow it out or reignite it. The nuclear reactions deep in the core transforms 600 million tons per second of hydrogen into helium using a chemical processes called the proton-proton chain.
  4. When a star uses up its fuel, the way it dies depends on how massive it was to begin with. Large stars can go supernova and collapse in on themselves indefinitely, forever.
  5. By looking at oddball things that happen around the black hole.  For example, light getting distorted and forming streaks and multiple images where there should be only one object, or watching an object get yanked about without anything visible around to the pulling, x-rays and gamma ray jets, or the accretion disk ring lighting up.
  6. You would see white headlights coming from the front of your car, but a friend sitting on the ground miles ahead of you, watching you race toward them would see you turn on blue headlights.
  7. Take your pick: MASERs shooting out of the poles of Jupiter; the way Jupiter shocks Io with 3 million amps every time it crosses its magnetic fields; Io belching itself inside-out; needing windshield wipers if you stay in orbit around Io… the list goes on and on.
  8. Most people settle their focus on Neptune and/or Venus after the teleclass.
  9. Barnard 68 is an example of a dark nebula.  It absorbs all light (energy) and is the coldest spot we’ve ever found out there in the universe. The stars are still there, but behind the dark cloud.
  10. Planets don’t twinkle, but stars do.  It’s an easy way to spot Jupiter, Saturn, Venus, and Mercury.
  11. You can see our Moon, four moons of Jupiter (Ganymede, Io, Europe, and Callisto), and four of Saturn.

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Design a Solar System

Sunday December 13, 2009

mysolarsystem-thumbnailWhat would happen if our solar system had three suns?  Or the Earth had two moons? You can find out all these and more with this lesson on orbital mechanics. Instead of waiting until you hit college, we thought we’d throw some university-level physics at you… without the hard math.
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To get you experienced with the force of gravity without getting lost in the math, there’s an excellent computer program that allows you to see how multi-object systems interact. Most textbooks are limited to the interaction between a very large object, like the Earth, and much smaller objects that are very close to it, like the Moon. This seriously cuts out most of the interesting solar systems that are out there in the real universe.


The University of Colorado at Boulder designed a great system to do the hard math for you. Don’t be fooled by the simplistic appearance – the physics behind the simulation is rock-solid… meaning that the results you get are exactly what scientists would predict to happen.


How do I design a solar system?

Go to the My Solar System simulation on the PhET website and carefully follow the instructions for each activity. Answer the questions and record your results before going on to the next activity. Click here to RUN the simulation on the internet.


Here’s what you should see and do:



Download Student Worksheet & Exercises


Exercises:


  1. What effect does changing the mass of orbiting planet have on the diameter of the orbit?
  2. What effect does changing the speed have on a planet’s orbit?
  3. What happens to the planet’s orbit when you increase the initial distance between the planet and the Sun?
  4. Find the mass values needed for a stable orbit. Circle the values on the table that make a stable orbit.
  5. Why don’t a feather and a brick hit the ground at the same time?

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Star & Planet Trails

Sunday December 13, 2009

These are a set of videos made using planetarium software to help you see how the stars and planets move over the course of months and years. See what you think and tell us what you learned by writing your comments in the box below.


What’s odd about these star trails?

You can really feel the Earth rolling around under you as you watch these crazy star trails.
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Download Student Worksheet & Exercises


Do the planets follow the same arc across the night sky? You bet! All eight planets follow along the same arc that the sun follows, called the ecliptic. Here’s how the planets move across the sky:



Exercises:


  1. If you have constellations on your class ceiling, chart them on a separate page marking the positions of the rocks with X’s.
  2. Tonight, find two constellations that you will chart. Bring them with you tomorrow using the technique outlined above in Experiment.

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Build a REAL Scale Model of the Solar System

Sunday December 13, 2009

Ever wonder exactly how far away the planets really are?  Here’s the reason they usually don’t how the planets and their orbits to scale – they would need a sheet of paper nearly a mile long!


To really get the hang of how big and far away celestial objects really are, find a long stretch of road that you can mark off with chalk.  We’ve provided approximate (average) orbital distances and sizes for building your own scale model of the solar system.


When building this model, start by marking off the location of the sun (you can use chalk or place the objects we have suggested below as placeholders for the locations).  Are you ready to find out what’s out there?  Then let’s get started.


Materials:


  • measuring tape (the biggest one you have)
  • tape or chalk to mark off the locations
  • 2 grains of sand or white sugar
  • 12″ beach ball
  • 3 peppercorns
  • golf or ping pong ball
  • shooter-size marble
  • 2 regular-size marbles

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Download Student Worksheet & Exercises


All distances are measured from the center of the sun. (In some cases, you might just want to use the odometer in your car to help you measure the distance!


Sun (12″ beach ball) at the starting point.


Mercury (grain of sand) is 41 feet from the sun.


Venus (single peppercorn) is 77 feet from the sun.


Earth (single peppercorn) is 107 feet from the sun.


Mars (half a peppercorn) is 163 feet from the sun.


Jupiter (golf or ping pong ball) is 559 feet from the sun.


Saturn (shooter-size marble) is 1,025 feet from the sun.


Uranus (regular-size marble) is 2,062 feet from the sun.


Neptune (regular marble) is 3,232 feet from the sun.


Pluto (grain of sand) is 4,248 feet from the sun.


Nearest Star (Alpha Centauri) is 5500 miles from the sun.


Is Your Solar System Too Big?

If these distances are too large for you, simply shrink all objects to the size of the period at the end of this sentence and you’ll get your solar system to fit inside your house using these measurements below.


First, draw a tiny dot for the Sun.  The diameter of the sun for this scale model is 0.1″, but we’re going to ignore this and all other planet diameters so we can fit this model within a 35′ scale.


We’re going to ignore the sizes of the planets and just focus on how far apart everything is. All distances listed below are measured from the sun.  Start by marking off the position of the sun with the tip of a sharp pencil.


Here are the rest of the distances you need to mark off:


Mercury is 4 inches from the sun.


Venus is 7.75 inches from the sun.


Earth is 10 inches from the sun.


Mars is 1′ 4″ from the sun.


Jupiter is 4′ 8″ from the sun.


Saturn is 8′ 6.5″ from the sun.


Uranus is 17′ 2″ from the sun.


Neptune is 26′ 11″ from the sun.


Pluto is 35′ 5″ from the sun.


Our nearest star, Alpha Centauri, is approximately 46 miles from the sun.


Did You Notice…?

Are you mind-boggled yet? Did you notice how the solar system is really just ’empty space’? Our models shown here are too small to start bringing in the moons, but you can see why posters showing the planets are not drawn to scale.  What are your thoughts on this experiment? Tell us in the comment area below!


For Advanced Students:

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If you really want to play with the different distances on your own, use this orbital calculator online to help convert the distances for you.


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Solar System Treasure Hunt

Sunday December 13, 2009

After you've participated in the Planetarium Star Show (either live or by listening to the MP3 download), treat your kids to a Solar System Treasure Hunt!  You'll need some sort of treasure (I recommend astronomy books or a pair of my favorite binoculars, but you can also use 'Mars' candy bars or home made chocolate chip cookies (call them Galaxy Clusters) instead.

You can print out the clues and hide these around your house on a rainy day.  Did you know that I made these clues up myself as a refresher course after the astronomy presentation?  Enjoy!

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Astronomy Clues
Click here to download the PDF version or the Word DOC version.


Download Student Worksheet & Exercises

You can print out images of each planet and match them up with the clues indicated below.  Post images of each of the planets along with the clue for the next one to really make this an out-of-this-world experience!

The Sun (CLUE #1): Hand this one to the kids to get started.

This object is hot, but not on fire.
Explore the dryer but don’t perspire!

Mercury (CLUE #2): Hide this clue below in the dryer.

This planet is closest, but not the hottest.
Check the sock drawer, and don’t be modest!

Venus (CLUE #3): Hide this clue below in the sock drawer.

This planet is so hot it can melt a cannonball,
Crush spaceships, rain acid, and is in tree tall.

Earth (CLUE #4): Hide this clue below in a tree (or plant).

Most of this planet is covered with water.
Visit the bathtub without making it hotter.

Mars (CLUE #5): Hide this clue below in the bathtub.

This planet is basically a rusty burp.
Discover the refrigerator and take a slurp.

Jupiter (CLUE #6): Hide this clue below next to the milk.

A planet so large it can hold the rest,
Explore our library with infinite zest!

Saturn (CLUE #7): Hide this clue below with a stack of books.

This planet had rings, but not made of gold.
Explore near the front door like an astronaut bold!

Uranus (CLUE #8): Hide this clue below on the front door.

Smacked so hard it now rolls on its side,
Find the window that is ever so wide.

Neptune (CLUE #9): Hide this clue below by sticking it on a window.

Check the sink for hurricane,
gigantic blue farts, and diamond rain.

Pluto (CLUE #10): Hide this clue below near the sink with the TREASURE!

Instead of one there were two, then four…
Visit the mailbox for the one that is no more.

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Solar Flares

Sunday December 13, 2009

Why does the Sun flare? Unpredictably, our Sun unleashes tremendous flares expelling hot gas into the Solar System that can affect satellites, astronauts, and power grids on Earth. This close up of an active region on the Sun that produced a powerful X-class flare was captured by the orbiting TRACE satellite. The glowing gas flowing around the relatively stable magnetic field loops above the Sun's photosphere has a temperature of over ten million degrees Celsius. These flows occurred after violently unstable magnetic reconnection events above the Sun produced the flare. Many things about solar active regions are not well understood including the presence of dark regions that appear to move inward during the movie.

This is a real video of the sun captured from the Solar Dynamics Observatory:

Astrophysics not only looks at nearby planets and distant stars, it also deals with the center of our solar system: the Sun. Our Sun is not quite a sphere (it’s a little flat on one side), which actually made the initial calculations of Mercury’s orbit incorrect when we estimated it to be a perfect ball. Our Sun is a G-type star, and recent measurements indicate that our Sun is brighter than 85% of the stars in our own galaxy. It takes light about 8 minutes to travel from the Sun to the Earth, meaning that if the Sun were to suddenly and magically disappear, we wouldn’t know about it for 8 minutes.

The Sun is made of hot plasma and is 1.3 million times the size of our Earth. The Sun holds 99% of the mass of our solar system, but only has 1% of the momentum. It’s 74% hydrogen and 24% helium, with trace amounts of oxygen, carbon, iron, and neon. Scientists split the incoming light into a giant 40-foot rainbow and looked for signs of which elements are burning through a special instrument called a spectrometer (you’ll be building one of these in this section) to figure out the Sun’s composition.

With a 15 million oC core, the Sun is not on fire, but rather generates heat by smacking protons together and getting a puff of energy through a process called nuclear fusion. We can’t directly observe the core of the Sun, but we can figure out what’s going on inside by watching the patterns on the surface. You’ll learn more about this in the activity that covers helioseismology. The surface temperature of the Sun is about 5500oC, so it cools considerably when the gases bubble up to the surface.

The Sun rotates differentially, since it’s not solid but rather a ball of hot gas and plasma. The equator rotates faster than the poles, and in one of the experiments in this section, you’ll actually get to measure the Sun’s rotation. This differential rotation causes the magnetic fields to twist and stretch. The Sun has two magnetic poles (north and south) that swap every 11 years as the magnetic fields reach their breaking point, like a spinning top that’s getting tangled up in its own string. When they flip, it’s called “solar maximum,” and you’ll find the most sunspots dotting the Sun at this time.

The video below is taken from the very first images from the National Science Foundation's Daniel Inouye Solar Telescope. Do you see the bubbling, rolling surafe of the sun? The size of onen of the "cells" is about the state of Texas, or the size of France, just to give you an idea of scale.

The telescops is on top of a mountain in Hawaii that has a huge 13 foot mirror (the largest ever used ona solar solar telescope), and it also sits along with all the other instruments, on a 16.5 meter table weighing 100 tons that slowly rotates to track the position of the sun as it travels through the sky.

 

And if you want to see an image of the sun right now, you can visit SOHO's main page.

Want to safely view the sun yourself? Here's how to do it...


How to View the Sun Safely

Sunday December 13, 2009

You know you're not supposed to look at the sun, so how can you study it safely?  I'm going to show you how to observe the sun safely using a very inexpensive filter.  I actually keep one of these in the glove box of my car so I can keep track of certain interesting sunspots during the week!

The visible surface of the sun is called the photosphere, and is made mostly of plasma (remember the grape experiment?) that bubbles up hot and cold regions of gas. When an area cools down, it becomes darker (called sunspots). Solar flares (massive explosions on the surface), sunspots, and loops are all related the sun’s magnetic field. While scientists are still trying to figure this stuff out, here’s the latest of what they do know...

The sun is a large ball of really hot gas - which means there are lots of naked charged particles zipping around. And the sun also rotates, but the poles and the equator move and different speeds (don’t forget – it’s not a solid ball but more like a cloud of gas). When charged particles move, they make magnetic fields (that’s one of the basic laws of physics). And the different rotation rates allow the magnetic fields to ‘wind up’ and cause massive magnetic loops to eject from the surface, growing stronger and stronger until they wind up flipping the north and south poles of the sun (called ‘solar maximum’). The poles flip every eleven years.

There have been several satellites specially created to observe the sun, including Ulysses (launched 1990, studied solar wind and magnetic fields at the poles), Yohkoh (1991-2001, studied x-rays and gamma radiation from solar flares), SOHO (launched 1995, studies interior and surface), and TRACE (launched 1998, studies the corona and magnetic field).

Ok - so back to observing the sun form your own house. Here's what you need to do:

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Materials:

  • Baader filter film
  • set of eyeballs


Click here for an inexpensive Baader filter film. You can use these with your naked eye or over the OPEN END (not the eyepeice) of a telescope.  See image below:

 

Want to see a BIG solar flare?
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Recent Astronomical Events

Sunday December 13, 2009

Comet Shoemaker Levy Colliding with Jupiter

Spectacular images of Jupiter during and after impacts, when over twenty fragments of Comet Shoemaker-Levy 9 smashed into the planet in July 1994. Click here to read more.

Solar Flares caught by SOHO

This mega-flare was seen being spewed out by the Sun starting at 20:29 CET on 4 November 2003. This video sequence was captured by SOHO’s Extreme ultraviolet Imaging Telescope. Don’t worry about the image being green – it’s just the filter they used in order to see.Click here to read more.

In this video below, astronomers blocked out the sun (seen as a white circle in the center of the red disk) so they could see the action in the corona.

Space Shuttle Launch

Sunday December 13, 2009

Something every person should do in their lifetime is watch a rocket or space shuttle launch. Since this is getting harder and harder, and most folks don’t live in a convenient area for viewing launches, here’s one of the best launches filmed on video. STS-119 (ISS assembly flight 15A) was a space shuttle mission to the International Space Station (ISS) which was flown by Space Shuttle Discovery during March 2009.

It delivered and assembled the fourth starboard Integrated Truss Segment (S6), and the fourth set of solar arrays and batteries to the station. The launch took place on March 15, 2009, at 7:43 p.m. EDT. Discovery successfully landed on March 28, 2009, at 3:13 p.m. EDT.

The Great Observatories

Sunday December 13, 2009

Lyman Spitzer was a theoretical physicist and astronomer who worked on star formation and plasma physics. The scape telescope named after him is equipped with infrared imaging capability that enables the telescope to see through dust and gas clouds to reveal what lies underneath.

Spitzer is part of the 1970s idea NASA conceived for the Great Observatories. The idea was to have the Hubble Space Telescope operate in the visible range, Chandra which operates in the x-ray, and Spitzer which operates in the infrared. Here’s an informational video about Spitzer:

Subrahmanyan Chandrasekhar was one of the most careful, thorough, and impressive astronomers in the first part of the 20th century who worked in may different areas of astronomy, making great leaps with his discoveries. He won the Nobel prize for his ideas about when and how to get supernova, which he did while traveling on a boat at age 19! Chandra had a very elegant way of using mathematics to describe atmospheres of planets and stellar structures of galaxies. He was one of the few researchers that is able to teach as well as do his own research.

The Chandra X-Ray Observatory is the third of NASA’s Great Observatories. Chandra looks for high energy X-ray radiation, which appears near supernovae, supermassive black holes and neutron stars. Here’s an video about the telescope itself and how difficult it is to observe x-rays:

Recent Missions

Sunday December 13, 2009

NASA’s Deep Impact Mission

Launch and flight teams are in final preparations for the planned Jan. 12, 2005, liftoff from Cape Canaveral Air Force Station, Fla., of NASA’s Deep Impact spacecraft. The mission is designed for a six-month, one-way, 431 million kilometer (268 million mile) voyage. Deep Impact will deploy a probe that essentially will be “run over” by the nucleus of comet Tempel 1 at approximately 37,000 kilometers per hour (23,000 miles per hour). It’s like hitting a comet with something the size of a fridge. Click here to read more.

Galileo Probe Mission to Jupiter

Galileo was an unmanned spacecraft sent by NASA to study the planet Jupiter and its moons. Named after the astronomer and Renaissance pioneer Galileo Galilei, it was launched on October 18, 1989 by the Space Shuttle Atlantis on the STS-34 mission. It arrived at Jupiter on December 7, 1995, a little more than six years later, via gravitational assist flybys of Venus and Earth.

Galileo conducted the first asteroid flyby, discovered the first asteroid moon, was the first spacecraft to orbit Jupiter, and launched the first probe into Jupiter’s atmosphere.

On September 21, 2003, after 14 years in space and 8 years of service in the Jovian system, Galileo’s mission was terminated by sending the orbiter into Jupiter’s atmosphere at a speed of nearly 50 kilometres per second to avoid any chance of it contaminating local moons with bacteria from Earth. Of particular concern was the ice-crusted moon Europa, which, thanks to Galileo, scientists now suspect harbors a salt water ocean beneath its surface. Click here to read more.

Cassini-Huygens Mission to Saturn

The incredible journey to Saturn and Titan. Click here to read more.

New Horizons Mission to Pluto

This montage of New Horizons images shows Jupiter and its volcanic moon, Io. The images were taken during the spacecraft’s near-pass of the gas giant in early 2007. Credit: NASA/JHU/APL New Horizons’ voyage through the Jupiter system in 2007 provided a bird’s-eye view of a dynamic planet that has changed since the last close-up looks by NASA spacecraft. Click here to read more.

Fermi (GLAST) Mission

Sunday December 13, 2009

Enrico Fermi gave physics a give leap as he uncovered many puzzles in quantum mechanics and nuclear physics. Fermi had the rare ability to work with both experimental and theoretical physics who also could do the math and teach students in his spare time. He was awarded the Nobel prize at age 37 for figuring out what happens to the nucleus of an atom when you throw too many neurons at it (this induces radioactivity). Here’s a look at the mission that was named after him:

Kepler Mission

Sunday December 13, 2009

Johannes Kepler, a German astronomer famous for his laws of planetary motion. Check out our Johannes Kepler facts page for more information.
Johannes Kepler, a German astronomer famous for his laws of planetary motion. Check out our Johannes Kepler facts page for more information.

Kepler was the mind that pulled together the observations of Galileo and the data from Tycho to figure out how the planets moved around the sun.

Although his three laws were not recognized in his day (scoffed was more like it!), these laws are still used in today’s science classes. The Kepler mission launched in March, 2009, and is designed to search for Earth-like planets orbiting other stars. Here’s a video that details the mission:

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Historic Space Missions

Sunday December 13, 2009

Voyager Mission

In 1977, NASA launched two small spacecraft called Voyager 1 and Voyager 2. Weighing only 800 kgs each, they collected a wealth of scientific data and thousands of photographs of the four giant planets in our Solar System. After visiting Jupiter and Saturn, Voyager 1’s trajectory left the ecliptic plane in order to photograph Saturn’s moon Titan. This meant that Voyager 1 would not visit any other planets. However, Voyager 2 continued on to visit Uranus and Neptune. Still today, Voyager 2 is the only spacecraft to have visited these two “ice giants” and their moons.

Both Voyagers are still in operation and providing unprecedented data that engineers and scientists using today to understand space. Both are expected to last until 2020-2025, at which time their atomic battery life will no longer support their electrical systems.

 

Pioneer 10

Launched on March 2, 1972, Pioneer 10 was the first spacecraft to travel through the asteroid belt, and the first spacecraft to make direct observations and obtain close-up images of Jupiter. Pioneer 10 is now coasting silently through deep space (its last transmission was in 2003) toward the red star Aldebarran (the eye of Taurus the Bull), a journey of over 2 million years.  Originally intended as a 21-month program, this 30-year mission has more than paid for itself with discoveries and science.

 

Mariner 10 was a robotic space probe launched on 3 November 1973 to fly by the planets Mercury and Venus. It was launched approximately 2 years after Mariner 9 and was the last spacecraft in the Mariner program (Mariner 11 and 12 were re-designated Voyager 1 and Voyager 2). The mission objectives were to measure Mercury’s environment, atmosphere, surface, and body characteristics and to make similar investigations of Venus. Secondary objectives were to perform experiments in the interplanetary medium and to obtain experience with a dual-planet gravity-assist mission.

During its flyby of Venus, Mariner 10 discovered evidence of rotating clouds and a very weak magnetic field.

Mariner 10 flew past Mercury three times in total. Owing to the geometry of its orbit — its orbital period was almost exactly twice Mercury’s — the same side of Mercury was sunlit each time, so it was only able to map 40-45% of Mercury’s surface, taking over 2800 photos. It revealed a more or less moon-like surface. It thus contributed enormously to our understanding of the planet, whose surface had not been successfully resolved through telescopic observation.

Apollo 11/Saturn V Rocket Launch

Sunday December 13, 2009

This is the actual video of the very first moon landing of the Apollo 11 mission in 1969! Neil Armstrong was the first man to set foot on the moon with his now legendary words “One small step for man, a giant leap for mankind.” This is a truly amazing video. If you think about it, you have orders of magnitude more processing power in your mobile phone than they did in the whole space craft!! Incredible!

Retrograde Motion

Sunday December 13, 2009

mars-retrogradeIf you watch the moon, you’d notice that it rises in the east and sets in the west. This direction is called ‘prograde motion’. The stars, sun, and moon all follow the same prograde motion, meaning that they all move across the sky in the same direction.

However, at certain times of the orbit, certain planets move in ‘retrograde motion’, the opposite way. Mars, Venus, and Mercury all have retrograde motion that have been recorded for as long as we’ve had something to write with. While most of the time, they spend their time in the ‘prograde’ direction, you’ll find that sometimes they stop, go backwards, stop, then go forward again, all over the course of several days to weeks.

Here are videos I created that show you what this would look like if you tracked their position in the sky each night for an year or two.

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Mercury and Venus Retrograde Motion

This is a video that shows the retrograde motion of Venus and Mercury over the course of several years. Venus is the dot that stays centered throughout the video (Mercury is the one that swings around rapidly), and the bright dot is the sun. Note how sometimes the trace lines zigzag, and other times they loop. Mercury and Venus never get far from the sun from Earth’s point of view, which is why you’ll only see Mercury in the early dawn or early evening.

Retrograde Motion of Mars

You’ve probably heard of epicycles people used to use to help explain the retrograde motion of Mars. Have you ever wondered what the fuss was all about? Here’s a video that traces out the path Mars takes over the course of several years. Do you see our Moon zipping by? The planets, Sun, and Moon all travel along line called the ‘ecliptic’, as they all are in about the same plane.

 
Download Student Worksheet & Exercises

Exercises

  1. During which of the months does Mars appear to move in retrograde?
  2.  Why does Mars appear to move backward?
  3. Which planets have retrograde motion?

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Satellite Crash!

Sunday December 13, 2009

The Hubble Space Telescope (HST) zooms around the Earth once every 90 minutes (about 5 miles per second), and in August 2008, Hubble completed 100,000 orbits! Although the HST was not the first space telescope, is the one of the largest and most publicized scientific instrument around. Hubble is a collaboration project between NASA and the ESA (European Space Agency), and is one of NASA’s “Great Observatories” (others include Compton Gamma Ray Observatory, Chandra X-Ray Observatory, and Spitzer Space Telescope). Anyone can apply for time on the telescope (you do not need to be affiliated with any academic institution or company), but it’s a tight squeeze to get on the schedule.

Hubble’s orbit zooms high in the upper atmosphere to steer clear of the obscuring haze of molecules in the sea of air. Hubble’s orbit slowly decays over time and begins to spiral back into Earth until the astronauts bump it back up into a higher orbit.

But how does a satellite stay in orbit? Try this experiment now:

Materials:

  • marble
  • paper
  • tape

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Download Student Worksheet & Exercises

Troubleshooting: Expect to find marbles flying everywhere with this experiment! This quick activity demonstrates the idea of centripetal (centrifugal) acceleration. What happens when you circle the cone too slow or too fast? The marble itself is the satellite (like HST), and the cone’s apex (tip) is the Earth. When the marble zooms around too slow, it falls back into the Earth. So what keeps it up in “orbit”?

The faster an object moves, the greater the acceleration against the force of gravity (toward the Earth in this case). Think back to the Physics lab – when a marble went too slow through the roller coaster loop, it crashed back to the floor. When it went too fast, it flew off the track. There was a certain speed that was needed for the marble to stay in the loop and on course. The same is true for satellites in outer space.

If you have trouble with this experiment, just replace the paper cone with a disposable cup with a lid and try again (with the lid in place), and see if you can keep the marble circling around the top rim.

Exercises

  1.  What happens when your marble satellite moves too slowly?
  2.  What happens when the marble satellite orbits too fast?
  3. What effect does changing the marble mass have on your satellite speed?
  4.  How is this model like the real thing?

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Unit 7: Astrophysics Video

Sunday December 13, 2009

6-newtonianThere are TWO videos for this Astronomy Lesson, both of which cover different parts of astronomy. The first video is all about telescopes, and I’ll walk you step by step through what it’s really like to get a telescope, set it up and work with one of these super cool instruments. After you’re done with this video, click over to the experiments section where you’ll have a front-row seat to a planetarium-style star show.

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Want to buy a telescope?

What if you and I went shopping together for everything you needed to get started with telescope viewing? Would you like to see what I would recommend getting started with? Note that these are my personal recommendations I would select for my own kids. These items listed below are entirely OPTIONAL and not required for this unit on Astronomy. I do not receive anything for giving you these links – think of these items below as a referral from one hobbyist to another. Bookmark this page so you have these recommendations for when you need it.

  • SkyQuest XT8i Computerized IntelliScope This is the best deal for the dollar on the market, and the mount is low and stable enough for astronomers of all ages to use easily. If you’re in the market for an expensive, compact scope, then the Celestron 8″ SCT is the one to seriously consider. Note that both these scopes have exactly the same size mirrors, only the SCT never needs alignment.
  • Padded Telescope Case Don’t even think about skimping on the case!  Get a good one to protect your investment for years to come.
  • EZ Finder II Telescope Reflex Sight This will save you hours of frustrations over using the included finder-scope. Simply swap it out with the finder-scope and you’re good to go.
  • Variable Polarizing Telescope Filter This is like putting sunglasses on your scope so you can look at the moon without blinding your eyes. (This is NOT for the sun – that requires a solar filter.) It’s variable so you can change the amount of incoming light as the moon waxes and wanes.
  • LaserMate Deluxe Telescope Collimator This nifty device will keep your telescope in proper alignment so your views are at their best.
  • Stratus Wide-Field Telescope Eyepieces Get the 17mm eyepiece (or closest size) first, and you’ll be blown away by how much more you can see over the small eyepieces that come with the scope.  You can optionally get a carrying case to hold all your optical gear in a safe place.
  • Green Laser Pointer Get this one for Dad or Grandpa to play with as you point out the constellations to your kids.  Don’t put it on your scope in the special bracket they sell with it, as the laser will burn out quickly if you leave it on for too long (that’s what they don’t tell you in the ad for the bracket). The laser isn’t something to get your kids – it’s too bright and dangerous to use indoors and should only be used by adults outside… and only for astronomy.

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Buying a Telescope: How to Avoid Being Ripped Off

Thursday December 10, 2009

6-newtonianIf your kid is crazy for Astronomy, get your hands on a $25 copy of Guy Ottewell’s Astronomical Calendar. You won’t find a better, more complete yearly almanac of astronomy anywhere. (In fact, most sources use Ottewell’s information in their publications.)

If a telescope is in your near future, here are a few of my personal recommendations. (Please note that I do not sell any of these telescopes, nor do I get paid for posting these links.  Think of this as a sneak peek into my personal collection.)

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Best beginner’s telescope for kids is the 8? Dob by Orion. This is the telescope they’ll have through college. The eyepiece isn’t sky-high, nor is the price.  The mount is near the bottom of the scope, making it easy for kids to operate. The best way to learn the night sky is to get a scope and start looking around.  If you’re nervous about finding things to point to, then you might want to look at this telescope, which finds objects for you – the 8? GO-TO Dob. If your kid has already mastered telescope operation and you’re looking for an upgrade, then have a look at one of my personal favorites –  8″ Reflector. This is the scope I use the most when working with families and public events. Click here for an instructional video on how to use a telescope (including a peek at my 8″ Reflector mentioned above).

Your new telescope is going to come with two hard-to-use and practically useless eyepieces.  Toss them out and order a set of the best eyepieces on the market for your dollar, the Widefield Stratus. Make sure you get at least one when you purchase your telescope. If you’re only getting one, make it a 17mm –  this one’s best for close-up planetary and lunar viewing as well as deep sky viewing.

If you’re wanting to do a lot of lunar viewing, pick up a variable 1.25? polarizing filter . They’re like sunglasses for your telescope, as the moon is very bright compared with everything else! The rest of the filters, like the colored filters, UV and pollution blockers, and O-III filters you can wait on. As a beginner, you’re not going to know how and when to use thes, nor are you going to see much of a difference when you do.

Don’t forget to get padded cases to keep your telescope protected. Although it’s tempting to keep your telescope uncovered and on display, don’t. You need to keep your optics clean and scratch-free.

If you don’t mind shopping around for a bargain, you can find great deals for telescopes at AstroMart.

Shoestring Budget Telescopes Kids can make their own small refractor telescope or use a tabletop Dobsonian telescope, but these are both only good for viewing the moon and things like birds and trees.

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Space Station Tour

Tuesday December 8, 2009

This is a FOUR-PART video series that takes you on a complete tour of the International Space Station, guided by a NASA astronaut and filmed in the summer of 2009. Enjoy!

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Astronomy Lecture Series

Tuesday December 1, 2009

8x10.aiThis lecture series is from an astronomy course at Ohio State. It’s a 20-week college-level course, so don’t feel like you’ve got to do it all in one night!  You’ll learn about the solar system, planets, and universe through a well-organized set of lectures that really brings astronomy, human history, and current technology together. This content is appropriate for advanced students and above.

Why bother offering high school students these college-level classes? Because if you’re like me, you’re always thirsty for more, and you’re not picky about where it comes from.  If you learn just one new thing from these astronomy talks, then you are one step further along your science journey and it was worth your time.

You can either download the podcasts to your MP3 player or directly access the MP3 files.  There are slides along with the lectures, but don’t feel like you have to use them – the lectures are meaty enough on their own.  Ready?

Click here to access Prof. Roger Pogge’s Astro 161 Lectures (Part 1)

Click here to access Prof. Roger Pogge’s Astro 162 Lectures (Part 2)

Advanced High School Course in Radio Astronomy

Sunday November 22, 2009

Radio antenna dishes of the Very Large Array radio telescope in New Mexico.
Radio antenna dishes of the Very Large Array radio telescope in New Mexico.

This experiment is for advanced students. Radio astronomy is the study of radio waves originating outside the Earth. The radio range of frequencies or wavelengths is loosely defined by three factors: atmospheric transparency, current technology, and fundamental limitations imposed by quantum noise. Together they yield a boundary between radio and far-infrared astronomy at frequency 1 THz (1 THz =1012 Hz) or wavelength =0.3 mm.

If you’re an advanced high school-age student with a yearning to learn more about radio astronomy, you’re in the right place. First, you’ll get a college-level course about the fundamentals of radio astronomy with a full textbook, and you’ll also find problem sets with solutions and also a final exam.The lab included will have you building your very own radio telescope for under $100. Feel free to build the telescope as you work through the text or straight off the bat. If you’re allergic to math, just skip over those sections to get at the really interesting stuff. Click here to download the full text or use the links below.

Advanced Telescope Building

Tuesday September 15, 2009

So you’ve played with lenses, mirrors, and built an optical bench. Want to make a real telescope? In this experiment, you’ll build a Newtonian and a refractor telescope using your optical bench.

Materials:

  • optical bench
  • index card or white wall
  • two double-convex lenses
  • concave mirror
  • popsicle stick
  • mirror
  • paper clip
  • flash light
  • black garbage bag
  • scissors or razor
  • rubber band
  • wax paper
  • hot glue

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Build a Reflector and Refractor Telescope

Download Student Worksheet & Exercises

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