1. SURFACE

2. The outermost covering or layer.

3. EARTH

4. The planet that all known life exists on.

5. SUN

6. The star at the center of our solar system that supplies heat and light to Earth; its enormous gravity keeps the solar system in orbit.

7. WEIGHT

8. The heaviness of an object; force of gravity on mass = weight.

9. CRATERS

10. Bowl-shaped indents or cavities on the surface of a planet, moon, or asteroid that are caused by a collision with another object, such as a meteorite.

11. MOON

12. A natural satellite that orbits a planet; some planets have no moons; others have over 60 moons.

13. STAR

14. A flaming ball of gas in space, producing its own heat and light.

15. PLANET

16. One of the eight named objects that orbits the Sun.

17. ATMOSPHERE

18. A layer of gases surrounding an object in space.

19. METE0RITE

20. A relatively small chunk of space rock that strikes the surface of a planet or moon.