Earth's Formation ESS1-6 Vocabulary Review

2. Star nursery
3. The accumulation of particles into a massive object by gravitationally attracting more matter
9. Oldest materials found on Earth, 4.4 billion years old
13. planets made up of metals or rocks with a solid surface, and are also known as rocky planets; Mercury, Venus, Earth, and Mars
15. A large body of matter in orbit around the Sun or a star and thought to be developing into a planet
16. A solid, irregularly shaped rocky mass that is smaller than a planet and orbits the Sun; made up of materials similar to those that formed the planets,such as clay, silicate, nickel, and iron
17. A small body of accreted gas and dust thought to have orbited the Sun during the formation of the planets
18. When gravity causes matter to come together and form larger bodies

1. A period of increased impact from meteorites during the formation of the solar system
4. also known as the gas giants; formed beyond the frost line; Jupiter, Saturn, Uranus, and Neptune
5. The theory that states that the Sun and the planets in our solar system formed from a large cloud of interstellar gas and dust that collapsed and condensed over time.
6. A contracting mass of gas that represents an early stage in the formation of a star, before nucleosynthesis (fusion) begins
7. any natural object found in outer space, such as a star, planet, moon, asteroid, comet, or galaxy, that astronomers study and classify
8. process where an object in space, like a star or cloud of gas, shrinks down because of its own very strong gravity; caused a protostar to form at the center of our galaxy
10. A rotating disk of matter surrounding a large object in space, caused by the pull of gravity
11. a planet that once existed between Earth and Mars; slammed into the Earth and the moon was formed from the debris of the impact
12. The spontaneous emission of radiation by an unstable nucleus
14. A technique used to date materials such as rocks and carbon