Midterm Vocabulary Review

4. a model that places the Earth in the center of the universe and the planets and stars revolve around it.
6. a huge collection of stars, gas, and dust.
9. when Earth’s rotation axis is tilted neither toward or away from the Sun.
11. precipitation that soaks into the soil.
12. when the majority of the moon is illuminated.
15. the line on which an object rotates.
16. a long, deep valley on the ocean floor through which old ocean floor sinks back toward the mantle.
19. the process by which water vapor turns into liquid.
20. large objects made of dust and ice that orbit the Sun.
22. a very large, thick mass of ice that stays frozen from one year to the next and has the ability to move.
23. water that is saltier than fresh water, but not as salty as seawater
24. the orbit of one object around another object.

1. a chunk of rock or metal from space that falls through the atmosphere, or layer of gasses, surrounding Earth.
2. a person who studies the topography of the ocean floor.
3. the total amount of water on a planet.
5. The concentration of dissolved salt in a given volume of water.
7. consists of the Sun and everything that orbits, or travels around, the Sun.
8. an occurrence during which the Moon’s shadow appears on Earth’s surface.
9. when a liquid changes into a gas.
10. the central, darker part of a shadow where light is totally blocked.
13. underwater mountains that do not reach the surface.
14. phases of the Moon during which more of the Moon’s near side is lit each night.
16. a stream or river that flows into and joins a main river.
17. the water found underground in the cracks and spaces in soil, sand and rock.
18. areas of salty water that fill enormous basins on the Earth's surface.
21. an idea that the universe, as we know it, started with an infinitely hot and dense single point that inflated and stretched.