| Term | Definition |
|---|---|
| asteroid | a small, rocky object that orbits the Sun |
| comet | a small, orbiting body made of dust, ice and frozen gases |
| meteor | a streak of light caused by a chunk of matter that enters Earth's atmosphere |
| meteorite | a meteoroid that hits the ground |
| meteoroid | one of the chunks of matter that enters Earth's atmosphere and causes a meteor. |
| planet | a large body that revolves around the Sun |
| solar system | the Sun and all the bodies that revolve around it |
| inner planets | the four planets closest to the Sun |
| outer planets | the four planets farthest from the Sun |
| light-year | the distance that light travels in one year |
| magnitude | the brightness of a star |
| star | a large sphere of glowing gases |
