Stars and Galaxies Answer Key
1. The three types of galaxies are spiral, ________.
b. elliptical, and irregular
2. When a massive star explodes in a supernova, it can create ________.
a. a nebula
3. Stars are born in ________.
4. Stars produce energy through ________.
a. nuclear fusion
5. Galaxies are usually about ________ light years across.
6. The Milky Way is ________ light years across.
7. The Milky Way contains about ________ stars.
c. 100 billion
8. A black hole is ________.
a. a massive star that used up its fuel and collapsed
9. Scientists estimate that the Big Bang occurred ________.
b. 15 billion years ago
10. It takes light from the Sun ________ to reach Earth.
c. 8 1/2 minutes