| A | B |
|---|
| revolution | one full orbit around the sun |
| axis | an imaginary line around which an object spins |
| solar flare | an explosive eruption of waves and particles into space |
| rotation | one whole spin of an object on its axis |
| orbit | the path an object takes as it revolves around a star, planet, or moon |
| constellation | a group of stars that forms a pattern |
| comet | a frozen mass of different types of ice and dust orbiting the sun |
| moon | a natural object that revolves around a planet |
| planet | a large, round object that revoloves around a star and has cleared the region around its orbit |
| dwarf planet | a large, round object that revolves around the sun but has not cleared the region around its orbit |
| outer planet | any of the four planets in our solar system beyond Mars |
| inner Planet | any of the four closest planets to the sun |
| asteroid | a rocky mass up to several hundred kilometers wide that revolves around the sun |
| space probe | a spacecraft that gathers data without a crew |
