Celestial bodies

2. A large lump of ice and dust that orbit the Sun. They glow and produce a tail.
6. A large lump of rock and metal, smaller than planets, that orbit the Sun.
9. A ________ is a collection of billions of stars and other objects held together by the force of gravity.
11. A _____ is a luminous object made up of gas. It provides light and heat through nuclear reactions.
14. someone who studies stars and other objects in space.

1. Edwin _________ discovered that the universe is expanding.
3. A planet has to have cleared the region around its _____ of other celestial bodies.
4. Force that keeps the planets in a curved orbit around the sun.
5. Our galaxy is called the __________. (2words)
7. Our _______ consists of a star (the sun) and all the celestial bodies that orbit it. (2 words)
8. Cosmic background ________ gives evidence for the big bang theory.
10. A theory which provides an explanation for the origin of the universe.
12. Example of a dwarf planet.
13. A natural satellite of a planet.