| A | B |
|---|
| asteroid | a small rocky mass, which orbits the Sun- often found between the orbits of Mars and Jupiter |
| astronomy | the scientific study of objects and their properties outside the Earth’s atmosphere |
| atmosphere | a layer of gases surrounding a planet |
| climate | the average of weather conditions for a region |
| day | the time required for a planet or moon to rotate once on its axis |
| gravity | the force of attraction between all masses in the universe |
| inertia | the tendency of an object to keep moving in a straight line |
| International Space Station | A satellite habitat orbiting the Earth that is a place for different countries to conduct research |
| moon | a small planet-like body that orbits a planet |
| ozone layer | layer of the Earth’s atmosphere that protects us from the harmful rays of the Sun |
| planet | a large, spherical object made of rock or gas that orbits the Sun |
| solar system | the Sun and all the objects that orbit it |
| space shuttle | a vehicle that carries astronauts back and forth between Earth and outer space |
| star | a gigantic ball of very hot, glowing gasses |
| Sun | the star that is the central and largest body in our solar system |
| year | the time it takes for a planet to complete one revolution around a star, such as the Sun |
| Mercury | a small, rocky planet that’s always very hot on one side and very cold on the other |
| Venus | a small, rocky planet with a thick layer of poisonous, yellowish clouds |
| Earth | a small, rocky planet, which supports a variety of life |
| Mars | a small, rocky planet with very strong winds and dust storms – also known as the “Red Planet” |
| Jupiter | the largest planet with a storm, which can be seen in its Giant Red Spot |
| Saturn | a giant gas planet with the most rings, made mostly of water and ice |
| Uranus | a giant gaseous planet that orbits the Sun on its side |
| Neptune | a blue gaseous planet that has the fastest winds in the Solar System |
