# When Spaceships Sail on Sunbeams

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.

# When Spaceships Sail on Sunbeams

May 31, 2015

When rockets take off, huge clouds of smoke and steam rush out from under them, as they burn fuel to fly through the air. But what if a spaceship could just ride on sunlight? That’s what the new LightSail spacecraft will do. It turns out that light beams can actually push an object if it weighs little enough. This satellite, called CubeSat, is just a little block of equipment, but out of it pops a giant, super-thin, super-shiny sail. The 18-foot-wide sail gets “blown” by the Sun’s light, the same way a boat’s sail catches the wind. No fuel, no heavy rocket boosters — just a sail! Bill Nye the Science Guy and Neil Tyson, the famous astrophysicist, are leading the project, and are trying to gather the rest of the \$5 million needed for LightSail’s take-off. Most rocket launches cost hundreds of millions of dollars, so this sun-surfing ship sounds like a sweet deal.

Wee ones: What shape is the sail? How many edges does it have?

Little kids: If the satellite will launch at 2:00 pm on launch day and the sail will pop out 2 hours later, at what time will the sail open?  Bonus: There are 8 major planets going around the Sun. If LightSail visits all but 3, how many planets does it visit?

Big kids: As of this writing, 15,223 people had donated money to help launch LightSail. If you were the next “backer,” what number backer would you be?  Bonus: If LightSail sails 60 million miles to reach Mars, then another 310 million miles to reach Jupiter, how many miles has it flown?

The sky’s the limit — literally: If you thought you needed \$160 million to launch your satellite and just found out it costs only \$2 million each, how many satellites could you launch with that money?

Answers:
Wee ones: It’s square (maybe a rectangle if the sides aren’t exactly the same), and has 4 edges.

Little kids: At 4:00 pm.  Bonus: 5 planets.

Big kids: The 15,224th.  Bonus: 370 million miles.

The sky’s the limit: 80 satellites for the same money!

And thank you to Laurel P. for telling us about LightSail!

### 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.