| Term | Definition |
| axis | IMAGINARY LINE passing through the center of a planet |
| day | TIME needed for Earth to complete one rotation around its axis |
| astronomy | STUDY OF SPACE, including stars and planets |
| solstice | One of the two days in the year when hours f daylight and hours of darkness are at their GREATEST AND LEAST |
| equinox | One of the two days in the year when the hours of daylight EQUAL the hours of darkness all over the earth |
| Solar System | The Sun, its planets, and all other objects in orbit around the sun or planets |
| Satellite | An object that revolves around a larger object in outer space |
| Meteor | A piece of rock from space that enters earths atmosphere and burns, creating a bright streak of light across the sky |
| Moon | A natural object that revolves around a planet |
| Crater | A bowl-shaped hollow in the ground, caused by a volcano or meteor strike |
| Astroids | Objects made of rock, metal and ice that are much smaller than the planets and revolve around the sun |
| Comet | Solar system object made mostly of ice which follows a long narrow orbit around the sun. |