| A | B |
|---|
| Atmosphere | the air that surrounds the Earth; it is made of a mixture of gases |
| Axis | imaginary line about which an object rotates |
| Composition | the combination of substances that make up a whole object |
| Orbit | the path that one object in space follows as it revolves around another object in space |
| Revolution | one orbit of an object, such as a planet or satellite, in space around another object in space |
| Rotation | the spinning of a planet, Moon, or other object on its axis |
| How long for Earth to rotate? | 24 hours |
| How long for the Moon to orbit Earth? | 28 days |
