| A | B |
|---|
| celestial sphere | imaginary sphere |
| celestial object | object in sky outside the Earth's Atmosphere |
| Rotation | the turning of planets on its axis |
| Revolution | the movement of planets around the sun |
| Zenith | point in the sky directly above the observer |
| Terrestrial | planets made up of rocky crust and land |
| Jovian | Planets made up of gas |
| Auroras | glow in nighttime sky, produced by solar radiation hitting earth's magnetic field |
| Satallites | a smaller object revloving around a larger one. |
| Retrograde motion | when planets move eastward but periodically make westward loops |
| comet | A "dirty snowball" |
| Meteor | light made by a meteorid as it passes through the Earth's atmosphere |
| Astroid | large solid rock like masses |
| orbit | the path a celastial object takes around the sun |
| Elliptical orbit | ellipse shaped orbit with two foci |
| Heliocentric | planets revolve around the sun |
| Geocentric | planets revolve around the Earth |
| Perihelion | point in earth's orbit where earth and sun are closest |
| Aphelion | point in earth's orbit where the earth and sun are farthest apart |
