Across
- 8. Sudden brightening of a star
- 10. The distance light travels in one year
- 12. Stars with masses four times that of the sun that end in a brilliant explosion
- 13. States that the farthest galaxies are retreating the fastest
- 16. The remnants of supernova events
- 17. How bright a star actually is
- 18. The remains of low-mass and medium-mass stars
- 19. A star's brightness as it appears from Earth
- 21. An important tool used by astronomers to study stars
Down
- 1. Galaxies that are grouped together
- 2. The name for the universe beginning as a violent explosion from which the universe continues to expand, evolve, and cool
- 3. Pairs of stars pulled toward each other by gravity
- 4. About 90% of all stars
- 5. Dense objects with gravity so strong that not even light can escape their surface
- 6. A group of very bright stars
- 7. A developing star not yet hot enough to engage in nuclear fusion
- 9. Stars that get brighter and fainter in a regular pattern
- 11. Large groups of stars, dust, and gases held together by gravity
- 14. A designated area of the sky that contains a specific pattern of stars
- 15. A spinning neutron star that appears to give off pulses of radio waves
- 20. Extremely large stars