Astronomy Review

2. An average star that shrinks turns into this
4. A cloud of dust and gas
5. This shows how quickly galaxies are moving away from each other
8. A measure of the luminosity of a star
11. A large star that shrinks turns into this
13. A star so dense light cannot escape it due to its gravity
14. The distance light travels in one year
16. An outburst of light that occurs in areas of sunspot activity
19. The outer layer of the sun's atmosphere, this part of the sun has a very low density and can be seen only during a solar eclipse

1. Theory The widely accepted scientific theory that states 13-15 billion years ago, all matter and energy was compressed into a single dense point, and that this point exploded to create a continuously expanding universe
3. This is the second most dense object in the universe
6. A small, cool, and dark area located on the photosphere of the sun that follows an eleven-year cycle
7. star From a nova, a star turns into this
8. A measure of how luminous or bright a star appears to be from earth
9. How bright something is
10. The distance between the Earth and the sun; much smaller than a light year
12. This is the force that prevents the energy the sun generates through fusion reaction from causing the sun to explode
15. A system containing millions of stars that orbit a common mass and travel as one unit
17. A nuclear reaction that releases a lot of energy as hydrogen turns into helium
18. From a red giant, a star becomes this