Across
- 4. A force that pulls one object to a bigger object
- 5. The study of the universe
- 8. A nuclear reaction in stars to create hydrogen/helium
- 10. An explosion of a high mass star
- 11. Middle of our solar system
- 13. Planets that do not pass the asteroid belt are...
- 14. A person who thought the sun was in the center of the universe
- 17. The process of becoming bigger
- 18. A cloud of gas in a galaxy
- 19. A star that emits light when it pulse
- 20. Any physical substance
Down
- 1. The planet we live on
- 2. Earliest forms of matter, 1e-16 meters
- 3. A person who thought Earth was in the center of the universe
- 6. A point with infinite density
- 7. Gas Giants are considered...
- 9. The total energy a star can radiate per second
- 12. Massive celestial body
- 15. The emission of energy as electromagnetic waves
- 16. Everything in existence. Stars, gases, galaxies, black holes etc