Counting Stars with the Cows

Counting Stars with the Cows

November 17, 2018

Our friend Liam F. asked a great double-question: how many stars are in the universe, and how many can we see? Well, our own Milky Way “galaxy,” or clump of stars, has around 100 billion stars, and there are billions of galaxies out there…one astronomer guesses it’s a 1 with 24 zeroes after it (1,000,000,000,000,000,000,000,000 stars, or 1 septillion). So how many can we see with the naked eye? If you’re near big-city lights, the night sky won’t turn very dark, so you’ll see only about 500 stars on a clear night. Out in the countryside, though, the night sky will sparkle with stars — you might see up to 15,000! If you can drive at least 200 miles from a city, you and the cows will have many more stars to count.

Wee ones: Look out the window after dark. Can you see any stars in the sky? If you can’t, you can try again tomorrow night!

Little kids: If you can see any stars out your window, try to count as many as you can.  Bonus: If you can see 10 stars tonight but twice as many tomorrow, how many will you see tomorrow?

Big kids: Leo the Lion has 6 bright stars in his question-mark-shaped mane, and 3 more in his triangle body. If in a darker sky Leo shows 4 times as many stars, how many can you see then?  Bonus: You can divide the sky into equal-ish pieces, then count the stars in 1 piece to guess the whole sky. If you see 20 stars in each of 30 big pieces, how many stars can you see in total? (Hint if needed: What if there were just 2 stars in each piece?)

The sky’s the limit — for real: Which sky has more stars: a sky where you see 100 stars in each of 100 pieces, or a sky with 40 stars in each of 300 pieces?












Wee ones: Different for everyone…see if you can spot at least 1 bright star! It might be a planet if it isn’t twinkling.

Little kids: Again, different for everyone…try it on a clear night.  Bonus: 20 stars.

Big kids: 36 stars, since Leo has 9 bright ones.  Bonus: 600 stars.

The sky’s the limit: The sky with 40 each in 300 pieces. That one has 12,000 stars, while the other has just 10,000.

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About the Author

Laura Overdeck

Laura Overdeck

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.

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