| A | B |
|---|
| inner planets | planets between the asteroid belt and the sun |
| gas giants | large spheres made mostly of gases |
| orbit | a path an object takes when revolving around another object |
| outer planets | Jupiter, Saturn, Uranus, Neptune, and Pluto |
| comet | a small mass of ice and dust that orbits the sun |
| solar system | a group of objects in space that move around a central star |
| asteroids | objects that move between Mars and Jupiter |
| telescope | an instrument used to observe a distant object |
| satellite | an object that moves around another object in space |
| star | a burning sphere of gas |
| planet | a large object that moves around a star |
| axis | an imaginary line that Earth rotates around |
| space probe | a vehicle sent to explore space |
| phases | changes in the apparent shape of the moon |
| revolution | movement of Earth around the sun |
| rotation | the spinning movement of Earth |
| rock, ice crystals and dust | what rings around planets are formed by |
| planets that are close to the sun do this | orbit faster than the outer planets |
| water vapor | a space probe found this on Mars which may prove that liquid water once existed on Mars |
| Earth | the only planet that has liquid water |
| the sun | the source of almost all energy in our solar system comes from where? |
| 28 days | how long it takes the moon's cycle of phases to complete |
| Earth's seasons | caused by the it's revolutions and the tilt of its axis |
| refracting telescope | an instrument that uses lenses to magnify distant objects |
| Pluto | the outer planet that is NOT a gas giant |
