Across
- 4. 100 billion in each galaxy
- 5. dead average star
- 6. a sun and its family of planets
- 7. formed from the collapse of a red supergiant
- 8. beginning of the universe
- 9. explains how stars and planets are believed to form
- 10. our galaxy
Down
- 1. simplest element
- 2. baby star
- 3. 100 billion in the universe