Topic 1 Vocabulary Words

2. a ball of hot gas
4. the attractive force between objects; the force that moves objects downhill.
6. one of the different apparent shapes of the moon as seen from earth.
8. an oval shape, which may be elongated or nearly circular; the shape of the planets orbit.
11. a streak of light in the sky produced by the burning of meteoroid in earths atmosphere.
14. the darkest part of a shadow ( eclipse).
15. the movement of an object around another object.
16. the tendency of an object to resist a change in motion.
17. a pattern or grouping of stars that people imagine to represent a figure or object.
19. describing a model of the universe in which Earth is at the center of the revolving planet and stars.
20. an object that orbits a star, is large enough to have become rounded by its own gravity, and has cleared the area of its orbit.

1. either of two days of the year on which the sun reaches its greatest distance north or south of the equator.
3. the path of an object as it revolves around another object in space.
5. the part of a shadow surrounding the darkest part ( eclipse).
7. describing a model of the solar system in which earth and other planets revolve around the sun.
9. the spinning motion of a planet on its access.
10. either of the two days of the year on which neither hemisphere is tilted towards or away from the sun.
12. the partial or total blocking of one object in space by another.
13. an object that orbits a planet
17. a loose collection of ice and dust that orbits the sun, typically in a long, narrow orbit.
18. an imaginary line that passes through a planets center and its north and south poles, about which the planet rotates.
21. of universal gravitation