Chapter 13

3. Stars began as a large cloud of gas and dust called a ------
4. A large group of stars, gas, and dust held together by gravity
8. Often called the surface of the sun
9. After heavier and heavier elements form by fusion, the star expands into a --------
10. Areas of the Sun's surface that appear dark
12. The largest layer of the Sun's atmosphere
14. patterns of stars in the night sky
15. The gravity near this mass is so strong not even light can escape
16. A ------ is about the size of Earth and is very hot but can be very dim. It is a type of star

1. The leading theory about the formation of the universe
2. This layer extends upward about 2,000 km above the photosphere
5. The ------- of a star is a measure of the amount of light it gives off
6. These stars are so dense that a teaspoon would weigh more than 600 million metric tons in Earth's gravity
7. A measure of the amount of light received on Earth
11. The late stage of a star's life cycle
13. The distance that light travels in one year