Across
- 3. substance made up of various types of particles that occupies physical space and has inertia
- 7. formed when a massive star runs out of fuel and collapses
- 8. rocky objects that orbit the sun
- 13. a subatomic particle with the same mass as an electron
- 14. particles consisting of two protons and two neutrons tightly bound together
- 16. ball of hot gas
- 18. unzipped the universe 13.8 billion years ago
- 20. when two stars orbit around a common center of mass
Down
- 1. dust that occurs in outerspace
- 2. smaller version of an asteroid
- 4. when two light atomic nuclei combine two form one heavy one
- 5. measure of the fineness of gold
- 6. a disturbance that moves faster than the local sound of speed
- 9. the explosion of a star
- 10. dramatically changed the development of stars
- 11. where gold is mined today
- 12. the force by which a planet pulls objects towards its center
- 15. huge collection of stars, dust, and gases
- 17. the zone above and around our planet
- 19. formed by clouds of neutrons smashing into each other