| A | B |
|---|
| celestial sphere | an imaginary sphere encirlcing the earth on which all objects in the night sky appear. |
| celestial object | an object found in the sky outside of the earth's atmosphere. example the sun |
| rotation | the turning of an obkect on its axis |
| revolution | the movement of the Earth in its orbit around the sun |
| zenith | point in the sky directly above the obsever |
| terrestial | another name for inner planets, they have a rocky crust, a dense mantle layer, and a very dense core |
| auroras | a glow in the nighttime sky produced in the upper atmosphere by solar radiation hitting the earths magnetic feild |
| satellites | a smaller body revolving around a larger body; a natural satelliute is also called a moon. |
| retrogarde motion | a periodic backward, or westward, loop made by a planet in front of the background of constellations. |
| comet | a mass of rock, ice, dust, and gas revolving aound the sun, usually in a highly eccentric orbt |
| meteor | a light produced when a meterorite streaks through Earth's atmosphere |
| asteroid | many small planetlike bodies revolving around the sun between the the orbits of Mars and jupiter |
| orbit | the path f a revolving body such as that followed by earth revolving around the sun. |
| elliptical orbit | ellipse shaped orbits with two foci |
| heliocentric | model that has the sun at its center, as in heliocentric solar system |
| geocentric | model that has earth in its center as in a geocentric universe |
| perihelion | point in planets orbit when nearest sun |
| aphelion | the point in a planets orbit when it is farthest from the sun |
| jovian | gaseus planets that are much larger and less dense than terrestrial planets, all outer planets except Plutoe are terresrial planets |
