Across
- 4. collapsed core of a high mass star
- 5. start of expansion
- 7. cooler areas on surface
- 8. trillion years
- 11. oval shaped
- 12. New stars in the arms and old in the middle
- 14. cloud of gas
- 17. hottest layer of atmosphere
- 18. tells us galaxies are moving away
Down
- 1. warm rises cool sinks
- 2. spread out
- 3. squeezing atoms together
- 6. the raisins spread apart as the bread rises
- 7. stream of charged particles
- 9. apparent shift
- 10. bright center of a galaxy
- 13. fusion of h2 and He
- 15. collapsed neutron star, no light escapes
- 16. loop of gas