chp. 21 The Universe and Beyond

4. an apparent shift in the position of an object when viewed from different locations
5. a spherical or elongated galaxy with a bright center and very little dust or gas
10. a unit of length equal to the distance that light travels through space in one year
12. a star in which all the particles have become neutrons; collapsed remains of a supernova
16. radiation left over from the big bang that fills all of space
17. the rainbow of colors produced when white light passes through a prism or spectrograph
19. a galaxy with a bulge in the center and very distinctive spiral arms
21. a diagonal pattern of stars on the H-R diagram
22. a large grouping of stars in space
23. a star-like source of light that is extremely far away; one of the most powerful sources of energy in the universe
24. an object with more than three solar masses squeezed into a ball only 10 km across whose gravity is so strong that not even light can escape

1. a group of older stars that looks like a ball of stars
2. the theory that states that the universe began with a tremendous explosion
3. a spinning neutron star that appears to pulsate as its beam of light passes the Earth
6. how bright a light appears to an observer
7. the actual brightness of a star
8. a large cloud of dust and gas in interstellar space; the location of star formation
9. a small, hot star near the end of its life; the leftover center of an old star
11. the death of a large star by an explosion
13. the study of the origin and future of the universe
14. a graph that shows the relationship between a star’s surface temperature and its absolute magnitude
15. a galaxy that does not fit into any other category; one with an irregular shape
18. a star that expands and cools once it runs out of hydrogen fuel
20. a group of stars that are usually located along the spiral disk of a galaxy