| A | B |
|---|
| celestial sphere | imanginary sphere on which all objects appear in the sky |
| celestial object | the sun the moon or a planet or any distant object visible in the sky |
| rotation | the daily motion of the earth |
| revolution | an annual motion |
| zenith | point in the sky directly above the observer |
| terrestrial | another name for the inner planets |
| jovian | gaseous planets |
| auroras | a glow in the nighttime sky produced in the upper atmospere |
| satellite | a smaller body revolving around a larger body |
| retrograde motion | a periodic backward, or westward, loop made by a planet inthe background of constellations |
| comet | a mass of rock,ice dust and gas revolving around the sun, usually in a highly eccentric orbit |
| meteor | a light produced when a meteorite streaks throuh earthsatmospere |
| asteroid | many small planetlike odies revolving aroud the sun between the orbits of mars and jupiter |
| orbit | the path of a revolving body, such as the followed by earth revolving around the sun |
| ellipicalorbit | ellise-shaped orbit with two foci |
| heliocentric | model that has the sun at it's center, as in heliocentric solar system |
| geocentric | model that has earth at it's center, as in a geocentric universe |
| perihelion | point in planets orbit when nerest sun |
| aphelion | the point in a planet's orbit when it is farthest from the sun |
