Across
- 5. orbits the earth
- 8. the zone where life can happen
- 9. the center of our solar system
- 10. a group of billions of solarsystem
Down
- 1. a factor of gravity
- 2. balls of rock that orbit the sun
- 3. another factor of gravity
- 4. the force that pulls objects together
- 6. happens when a star explodes
- 7. the amount of matter a object contains