Key Vocabulary

Asteroid
Objects much smaller than planets that travel around the sun farther away from the Sun than Mars but closer to the sun than Jupiter.

Atmosphere
The layer of gases that surround a planet or moon.

Comet
“Dirty snowballs” with a tail that travel in long elliptical orbits around the sun. They are made of rock, ice, and gas and are millions of miles long. The most famous comet is Halley’s comet which orbits the sun every 76 years.

Crater
A round hole or pit in the ground made by a meteorite, or any falling object. The moon is covered with craters where it was hit by meteoroids.

Meteoroid
A space rock that floats through space. If it enters the Earth’s atmosphere it is called a meteor. Once it hits Earth it is called a meteorite.

Moon
A natural satellite that orbits around a planet. Moons can be large and small. The Earth has one moon. Jupiter has over 50 moons that orbit it.

Orbit
To travel around something in a circular motion. All the planets orbit around the sun. The orbit of Earth is smaller than the orbit of Jupiter because Earth is closer to the sun.

Sol
The Latin word for Sun.

Star
Large balls of hot gas that give off energy and light throughout the Universe. The Sun is a medium-sized yellow star in our Solar System. Some are bigger than the sun and some are smaller.

Sun
A medium-sized yellow star in our Solar System. The Sun gives us light and energy.

Telescope
A tool that scientists use to be able to see the stars closer up. It makes things look bigger than when we look at them with just our eyes. We can only see the planets Uranus, Neptune, and Pluto with a telescope because they are so far away.