| Word | Definition |
| Astronomy | The study of the moon, stars, and other objects in space. |
| Axis | An imaginary line that passes through Earth's center and the North and South poles, about which Earth rotates. |
| Rotation | The spinning motion of a planet about its axis. |
| Revolution | The movement of an object around another object. |
| Orbit | The path of an object as it revolves around another object in space. |
| Latitude | A measurement of distance from the equator, expressed in degrees north or south. |
| Solstice | The two days of the year on which the noon sun is directly overhead at either 23.5 degrees South or North. |
| Equinox | The two days of the year on which neither hemisphere is tilted toward or away from the sun. |
| Vernal Equinox | The day of the year that marks the beginning of spring in the Northern Hemisphere. |
| Autumnal equinox | The day of the year that marks the beginning of fall in the Northern Hemisphere. |
