It’s astronomy time! Here are three short readings, and three STEAM activities, for kids 8-12 to explore the multitude of stars in the sky and the vastness of the universe.
These lessons are offered under a Creative Commons Attribution 4.0 License (CC-BY 4.0): You’re free to re-distribute, remix and re-use on the condition that I’m credited. Enjoy!
On a clear-sky night, go outside (or open the window) and look up at the sky. What do you see?
If you live in or near a city, the sky you see at night is different from the night sky that almost everyone who has ever lived saw. George Washington, Queen Elizabeth I, Shakespeare, the Pharaohs: everyone who lived before about 1920 saw a different sky than today’s city-dwellers do. When they looked up at night, they saw thousands of stars. If George Washington had decided, one clear, moonless night, to stay up all night and count all the stars in the sky, he could’ve counted 4 to 5 thousand stars.
How many stars can you see at night? If you live in a big city, like Chicago or Boston, you might only be able to see about 35 stars on the clearest, darkest night! Today, cities put a lot of light into the sky. Even when it’s not cloudy, that city-light bounces off tiny particles of water in the air to make the sky glow faintly. That’s called “skyglow,” and it drowns out the light of all but the brightest stars.
This picture shows two views of the same stars: one from the countryside, and one from the city.
Picture by: Jeremy Stanley, CC-BY 2.0, Wikimedia Commons
Activity: Sprinkle on the stars
Are you in the city? You can give yourself an idea of the country sky with this activity. You’ll make a portrait of the sky you see, then sprinkle on more stars.
Time: 20 minutes before bed, 30 minutes the next day.
You will need:
- Black construction paper
- Flashlight with red tissue paper taped over it
- White crayon
- An old toothbrush
- White paint… OR glow-in-the-dark paint, if you have it!
- A small paintbrush
- An old shirt
- Pick a clear night and go outside, or look out the window.
- Bring: the paper, the crayon, and the flashlight.
- Draw the stars you see on the construction paper with the white crayon.
- Use the flashlight with red taped over it to see what you’re doing!
- The next day, put on the old shirt and get ready to paint.
- First, add paint to the stars you drew last night, to make them bigger and brighter.
- Take a look at the picture of Orion in the country vs. the city above. The country stars look so much bigger and brighter! Use the paint to make the stars on your picture bigger and brighter, too.
- Now it’s time to sprinkle on extra stars! Dip the very tips of the toothbrush bristles in the paint. Then use your thumb to splatter tiny drips of paint on the construction paper.
- Repeat until you have as much extra splatter as you’d like.
- Use the picture of Orion in the country vs. the city above for reference.
- Keep splattering until your picture looks as starry as the country one!
The Milky Way
Kids in cities a hundred years ago, like kids in the countryside today, could see something else that’s invisible from the city: a pale band of light called the Milky Way. The picture at the top of the page is a horizon-to-horizon shot of the Milky Way. It looks like a pale band of light, stretched across the sky.
Today, the Milky Way is so hard to see from the city that in 1994, when a power outage turned out all the lights in Los Angeles, dozens of people called 911 to ask about the strange thing in the sky!
Of course, the Milky Way doesn’t have anything to do with milk. It’s our galaxy. A galaxy is a lot of stars all clustered together in space, and the Sun is one of the stars in the Milky Way galaxy. The 4,000 stars that George Washington could’ve seen are only a tiny fraction of the stars in the Milky Way. Even on the darkest night, with the strongest telescope, we can’t see all of them. Astronomers think that our galaxy has hundreds of billions of stars. The light of all those stars is what gives the Milky Way its glow.
Picture by: Steve Jurvetson / CC BY (https://creativecommons.org/licenses/by/2.0)
Activity: A band of stars
If you live in the city, you can make your own Milky Way to hang over your bed! (And you won’t need a drop of milk.)
Time: Half an hour.
You will need:
- Several sheets of black construction paper
- White chalk OR a white crayon
- White paint
- Optional: Star-shaped stickers, glitter glue, glitter
- Tape together the construction paper, end-to-end, until you have a loooong band.
- Use the SIDE of the white chalk or crayon (peel the paper off the crayon) to lightly shade a cloud all the way down the middle of your long band, like the picture above.
- Use paint, star stickers, glitter, and/or dots of glitter glue to add stars to the cloud.
- Hang your Milky Way up over your bed, lie back, and stargaze!
If you’d like to learn more about the Milky Way, try this NASA article.
The Milky Way may have a hundred billion stars, but it’s only one galaxy. The Universe contains billions more galaxies, each with its own billions of stars. Just how many stars might be out there in the whole universe?
Astronomers think that just the part of the universe that we can see has more than a hundred billion galaxies. A hundred billion times a hundred billion is 10 000 000 000 000 000 000 000 stars. That’s a 1 with 22 zeros behind it. There are at least that many stars in the universe–and probably more. But most of them are too far away to be seen, even with the strongest telescope on the darkest night.
Activity: A grain of rice
Let’s use a bag of rice to visualise the scale and structure of our local corner of the universe.
Time: 20 minutes
You will need:
- A couple cups of dried rice (NOTE: Check with adults before using up all the rice!)
- A really fine-tip pen
- A clean floor
- A vacuum cleaner (for cleanup)
- Pick one grain of rice. Draw a little spiral galaxy on it, or just make a mark.
- This is our galaxy: the Milky Way.
- Imagine a hundred billion stars in this grain of rice.
- Take a rounded tablespoon of rice out of the bag (this is about 80-100 grains of rice). Add the Milky Way grain to it. Spread them out on the floor in a dumbbell shape.
- This is the “Local Group”, the group of galaxies that we’re in.
- The Local Group is kind of dumb-bell shaped.
- Every grain of rice represents a galaxy like ours.
- There are at least 80 galaxies in the Local Group.
- Now we’re going to ZOOM OUT! Take the Milky Way grain and draw a dumbbell over top of the spiral (or just change the mark).
- This grain is now the Local Group.
- Add a pinch more rice to the floor and drop the Local Group grain in it.
- This is the Virgo Supercluster.
- Now every grain of rice represents a galaxy group of 100-ish galaxies.
- There are about 100 galaxy groups in the Virgo Supercluster.
- Dump three more tablespoons of rice on the floor and spread them out.
- This is the Laniakea Supercluster… a kind of super-supercluster!
- Each tablespoon of rice is a supercluster like the Virgo Supercluster.
- Laniakea is a group of 4 Superclusters, including the Virgo Supercluster.
- Every grain of rice still represents a group of 100-ish galaxies.
- Now, add one whole cup of rice to the rice on the floor and spread it around in a long line.
- On an even BIGGER scale, superclusters are grouped together into even larger structures, called walls, sheets, or filaments.
- This is the filament we’re part of. It has 4 other superclusters in it, besides our supercluster Laniakea.
- Step back and take a look at the filament. Can you still see the Laniakea Supercluster in it?
- At a really big scale, the Universe is made up of sheets and filaments of galaxy groups, like this.
- In between the sheets and filaments is mostly empty space.
- Before cleaning up, have a think about the number of stars the rice on your floor represents.
- Each grain of rice on the floor is a group of 100 or so galaxies like the Milky Way.
- And in that group of 100 galaxies, each galaxy has 100 billion or so stars.
- So each grain of rice on your floor represents about a trillion stars.
- And this filament is only our little corner of the universe!
- And now… time to vacuum!
If you’d like to read more about the groups of galaxies around us, try these links:
The Local Group (NASA)
The superclusters in the Laniakea Supercluster (called the “Nearest Superclusters” on this page)
If you’d like to explore the gigantic SIZE of the universe further, try NASA’s Cosmic Distance Scale.
The picture of the Milky Way at the very top of the page is by Bruno Gilli/ESO, http://www.eso.org/public/images/milkyway/
This work is licensed under a Creative Commons Attribution 4.0 International License.