front 1 a small rocky body orbiting the sun | back 1 asteroid |
front 2 A mixture of gases that surrounds a planet or moon. | back 2 atmosphere |
front 3 A ball of frozen dust and rock that orbits the sun and has a tail that glows | back 3 comet |
front 4 A large round pit caused by the impact of a meteoroid. | back 4 crater |
front 5 A collection of stars, dust, and gas bound together by gravity | back 5 gravity |