1. Chapter 20 Sections 1-3 By: Shannon Harris

2. Astronomical Unit The average distance between the earth and the sun.

3. Terrestrial Planets The name for the inner planets

4. Prograde Rotation The counterclockwise spin of a planet or moon as seen from above the planet’s.

5. Retrograde Rotation The clockwise spin of a planet or moon as seen from above planet’s.

6. Gas Giants Very large planets that don’t have any known solid surfaces.

7. Satellites Natural or artificial bodies that revolve around larger bodies like planets.

8. Phases The different appearances of the moon due to its changing position.

9. Eclipse Occurs when the shadow of one celestial body falls on another.

10. Comet A small body of ice, rock, and cosmic dust loosely packed together.

11. Asteroid Small, rocky bodies in orbit around the sun.

12. Asteroid Belt A region of the solar system between the orbit of Mars and Jupiter.

13. Meteoroid A small body moving in the solar system that would become a meteor