Astronomy

4. a person trained to pilot a spacecraft, travel in a spacecraft or work in space
9. The process by which nuclei of atoms are formed
10. The rapid expansion of the universe
12. Small bodies believed to form through accretion
13. A cloud of gas and dust in space
14. The center of mass of two or more bodies

1. A dense, collapsing region within a nebula
2. The infinitely dense and hot point
3. The process by which larger celestial bodies break apart into smaller pieces
5. The process by which stars generate energy
6. National Aeronautics and Space Administration
7. A depression on a celestial body caused by a collision
8. is a form of transportation that travels regularly between two places in space
11. a huge collection of gas, dust, and billions of stars and their solar systems.
12. a celestial body distinguished from the fixed stars