Chapter 25 Vocabuary

2. Bang Theory The universe began as a violent explosion.
4. Dwarf The remains of low-mass and medium-mass stars.
8. A spinning neutron star that appears to give off pulses of radio waves.
10. A system of galaxies containing from several to thousands of member galaxies.
13. Stars exploding in a brilliant explosion.
14. Star A star that falls into the main sequence category on the H-R diagram.
16. Magnitude Measure of the amount of light a star gives off.
17. Clouds of dust and gases.
19. One of two stars revolving around a common center of mass under their mutual gravitational attraction.
20. A developing star not yet hot enough to engage in nuclear fusion.
21. Hole Dense objects with gravity so strong that not even light can escape their surface.

1. Year Distance that light travels in one year.
3. giant A very large, very red giant star.
5. Law A law that states that the galaxies are retreating from the Milky Way at a speed that is proportional to their distance.
6. Large group of stars, dust, and gases held together by gravity.
7. Stars Stars smaller and more massive than white dwarfs.
9. Magnitude Measure of the amount of light received on Earth.
11. variable Stars that get brighter and fainter in a regular pattern.
12. An apparent group of stars originally named for mythical creatures.
15. Giant A large, cool star of high luminosity.
17. Sudden brightening of a star.
18. The slight shifting in the apparent position of a nearby star due to the orbital motion of the Earth.