Across
- 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
Down
- 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