Across
- 5. all matter is composed of this
- 6. a system of millions or billions of stars, together with gas and dust,held together by the gravitational pull
- 9. he figured out how gravity works
Down
- 1. this is used to study light
- 2. A theory that suggest that our universe is expanding and was once much more denser that it is now.
- 3. made up of all matter and space that exists
- 4. the galaxy that we live in
- 6. the main reason why our universe exists
- 7. the star at the center of our solar system
- 8. an instrument that makes objects far away appear close