Stars, Galaxies, and Universes

2. This is so dense that light cannot escape the gravity.
5. Matter that we can't see but know exists; does not emit electromagnetic radiation.
8. Two stars orbiting each other.
10. A large red-colored start that is collapsing inward on itself.
11. Galaxies that are not spiral or elliptical.
12. Biggest group of stars; may contain hundreds of thousands of stars.
14. Nuclear fusion in the star's core produces helium from hydrogen.
16. Groups of up to a few thousand stars that are loosely held by gravity.

1. Egg-shaped rotating galaxy.
3. Ball of glowing gas at very high temperature.
4. Hypothetical form of energy, may make up as much as 71% of the energy in the universe.
6. Our galaxy
7. The study of the universe.
9. Arms that spiral outward off of spiral galaxies.
13. The leftover material in the core after a supernova explosion.
15. All of the star systems, galaxies, gas and dust.