| A | B |
|---|
| axis | an imaginary center line |
| revolution | one full orbit around the Sun |
| rotation | one whole spin of an object on its axis |
| solar system | the Sun, its nine planets, moons, asteroids, and comets |
| Mercury | the planet that is closest to the Sun |
| Venus | a planet with a thick layer of hot clouds covering a rocky surface |
| Earth | the planet that is one Astronomical Unit from the Sun |
| Mars | a rocky planet covered by red, dusty soil |
| Jupiter | a gas giant; the largest planet |
| Saturn | the least dense of all the planets |
| Uranus | the blue-green gas giant with an axis tipped farther than any other planet |
| Neptune | a deep blue gas planet that gives off more energy than it receives from the Sun |
| asteroid | a rocky mass up to several hundred kilometers wide that revolves around the Sun |
| comet | a frozen mass o diferent types of ice and dust that orbits teh Sun |
| Moon phases | the shapes of the lit side if the Moon that can be seen |
| satellite | a moon, rock, or any object that orbits another object |
| tide | the daily rise and fall of the oceans on Earth |
