Across
- 1. A collection of stars, gas
- 3. “dirty snowball” of ice and rocky debris
- 5. the fourth planet from the sun
- 9. a burst of light used to communicate.
- 11. a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member of a spacecraft.
- 12. turn around an axis or a center.
- 13. a single complete turn
- 17. any object takes as it revolves around another body or a center of gravity.
- 18. existing or occurring between collections of star syste,s
- 19. A distinctive pattern of stars
Down
- 2. how far and fast light travels
- 3. the solid outer shell of the earth
- 4. a mass that enters earths atmosphere
- 6. the rate of change of velocity
- 7. Hole light cant escape its gravitational pull once swallowed up.
- 8. someone who studies astronomy.
- 10. and immense cloud of gas and dust in interstellar space
- 14. any of numerous small celestial bodies that move around the sun
- 15. an object that orbits another object in space.
- 16. the gaseous envelope surrounding the earth or any other celestial body