Across
- 1. fusion of H2 and Helium
- 3. bright center of a disant galaxy
- 7. 9 trillion miles
- 10. tells us galaxies are moving away
- 12. stream of charged particles
- 15. warm rises, cool sinks
- 16. apparent shift
- 17. cloud of gas and dust
- 18. start of expansion
Down
- 2. irregular shape
- 4. the raisins move apart as the bread rises
- 5. squeezing atoms together
- 6. loop of gas
- 8. young stars in arms, and old stars in middle
- 9. collapsed core of high mass star
- 11. old stars
- 13. hottest layer of atmosphere
- 14. cooler areas on surface