Journey Into Space: Gravity, Orbits, and Collisions

Gravity, temperature, and atmosphere combine to make Earth our perfect home. Your challenge: Imagine how different it would be to try to live your life on another planet.

Moon Olympics
What would it be like to play sports on the moon? Go
What makes Earth a good place for human life? Go

Comet (kom-it)
An icy rock that travels around the Sun. Some comets appear to have bright tails.

Earth (urth)
The third planet from the Sun, it's located between Venus and Mars

Galaxy (gal-uhk-see)
A very large group of stars and planets such as the Milky Way

Meteor (mee-tee-ur)
A piece of rock and/or metal from space that enters the Earth's atmosphere at high speed, vaporizes, and forms a streak of light as it falls to the Earth. Most meteors - or shooting stars -- are as small as a grain of rice!

Moon (moon)
The satellite that moves around the Earth approximately once every 28 days and reflects light from the Sun

Planet (plan-it)
A large object circling the Sun

Satellite (sat-uh-lite)
1. A spacecraft that is sent into orbit around the Earth, the Moon, or another space object
2. A moon -- or other space object -- that travels in an orbit around a larger space object

Solar System (soh-lur siss-tuhm)
The Sun and the other space objects that move in orbit around it

Star (star)
A ball of gases in space