Hiding the Moon

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

Hiding the Moon

October 7, 2014

Tomorrow morning many of us will get to see a lunar eclipse, one of the coolest solar system events you can watch. The Earth will move right between the Sun and Moon to put its own shadow right on the Moon. During a lunar eclipse the Moon doesn’t totally disappear, because some sunlight still scoots around the edges of the Earth. Instead, a piece of the Moon turns reddish-orange as it slides into our shadow, until the whole Moon turns red; then the Moon slowly slides into the sunshine again. And this eclipse is extra special for the East Coast of the U.S. because it happens exactly at sunrise: the Moon will be setting in the west right when the Sun rises in the east! Meanwhile, an alien standing on the Moon would see a solar eclipse: the Earth will cover up the Sun completely. Whether you’re human or alien, if you’re up at 5:15 am New York time tomorrow, check it out!

Wee ones: If the Sun, Moon and Earth all play a part in the eclipse, how many heavenly bodies is that?

Little kids: The full moon (Moon exactly opposite the Sun) will happen at 6:51 am, and the middle of the eclipse will happen 4 minutes later. At what time will that be?  Bonus: If the eclipse starts at 5:15 in the morning and you get up an hour earlier, at what time do you get up?

Big kids: When the Moon goes into our shadow — after 13 1/2 days of sun — its temperature falls. If it drops 31 degrees from its high of 253 degrees F, how cool does it get?  Bonus: The eclipse will start at 5:15 am, and the middle of the eclipse will happen at 6:55 am. At what time will the eclipse end?

The sky’s the limit: The Moon and Sun look about the same size in the sky to us because the Sun is bigger by the same multiple that its distance from us is bigger. If the Moon is 2,200 miles wide and about 250,000 miles away from us, and the Sun is 93 million miles from us, about how wide is the Sun?




Wee ones: 3 heavenly bodies.

Little kids: At 6:55 am.  Bonus: At 4:15 am.

Big kids: 222 degrees.  Bonus: At 8:35 am, 1 hour 40 minutes after the midpoint, since the midpoint is 1 hour 40 minutes after the start.

The sky’s the limit: About 818,000 miles wide. Doing the mental math, if the Sun were 1 million miles away it would be 4 times as far from us as the Moon is, so if the Sun is 93 million miles it’s 372 times as far away. That would mean it’s 372 times as wide as the Moon, or 818,400 miles. The Sun is in fact about 864,000 miles, so that estimate came pretty close!

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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 while still in diapers, 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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