Across
- 2. the most abundant form of matter in universe
- 3. force of attraction between masses
- 4. dense that only neutrons exist in its core
- 6. the non-living parts of an ecosystem
- 9. stars, planets, gas, and dust
- 10. one celestial object moves in front of another
- 13. hits Earth’s atmosphere and burns up
- 14. the remnant of a supernova
- 15. the destruction of habitats
- 17. a safety device
- 18. the rate at which the universe expands
- 20. the distance that light travels in one year
Down
- 1. affect population and ecosystem
- 5. the resulting charge of an atom
- 7. positively charged centre of an atom
- 8. the SI unit of energy
- 11. an object composed of rocky material, ice, and gas
- 12. a galaxy that has an irregular shape
- 16. eclipse full Moon passes into Earth’s shadow
- 19. Way the galaxy that includes the solar system