Astronomy Review

5. a diagram used by astronomers to classify stars
8. the middle layer of the sun's atmosphere
9. the movement of one object around another object
10. the distance light travels in a year
12. more than 90 percent of all stars are this type
13. the brightness of a star depends upon both its size and ___________
15. day and night are caused by Earth's ________ on its axis
17. matter that does not give off electromagnetic radiation
19. the remains of a star with gravity so strong that even light cannot escape
20. the explosion of a giant or supergiant star
21. the name of our galaxy

1. the range of light that consists of different colors and wavelengths
2. a push or a pull
3. the amount of matter in an object
4. areas of gas on the sun's surface that are cooler than the gases around them
6. the building blocks of planets
7. when a star runs out of fuel, it becomes a ___________, a neutron star, or a black hole
11. the force that attracts all objects towards each other
14. the sun gets it energy from nuclear _________
16. a large cloud of gas and dust
18. where the sun produces an enormous amount of energy