Across
- 4. Come in shapes and sizes including spiral, elliptical or irregular. they are constantly moving away from each other.
- 5. region in space if infinite density where gravity is so strong that nothing, not even light can escape from it.
- 7. The smallest planet within our solar system.
- 9. The distance that light travels in one year
Down
- 1. The explosive death of a star.
- 2. A reaction in which two lighter atomic nuclei fuse, releasing energy.
- 3. A cloud of gas and dust in space.
- 6. The actual brightness of a star, measured using the absolute magnitude Scale.
- 8. Large balls of gas that undergo nuclear fusion.