Gravity & space
Why things fall, why astronauts float and how a satellite stays up. Play first, then read how it works.
Game
Lessons
Short reads with pictures. Many have a live experiment built in.
What is gravity?
Why things fall, why you stay on the ground, and why a feather and a hammer fall together on the Moon.
Same throw, four planets
Throw the same ball on Earth, the Moon, Mars and Jupiter and watch what gravity does.
Why don't satellites fall down?
They do fall! They just keep missing the ground. See how sideways speed turns a fall into an orbit.
How fast is orbit speed?
Why high satellites go slower than low ones, what an oval orbit is, and how fast you need to go to leave Earth for good.
Activity guides
Hands-on activities for home, class or self-study.