| Word | Meaning |
| Asteroid | A small celestial body with no definite shape that goes round the Sun |
| Orbit | The path a body follows as it travels round another body |
| Asteroid belt | The asteroid region between the orbits of Mars and Jupiter |
| Kuiper belt | The region beyond Neptune's orbit holding small bodies and leftover material |
| Trojans | Asteroids that travel round the Sun along a planet's own orbit |
| Near-Earth asteroids | Asteroids that cross the Earth's orbit |
| Ceres | The largest asteroid, 940 km in diameter |
| Eros | A long, narrow asteroid, 16.8 km in diameter |
| Diameter | The distance right across a body through its centre |