Chapter 4 Vocab

6. - greek word for color
9. - rocky objects, most of which are too small or too numerous to be considered a planet or dwarf planet.
11. - the motion one object around another.
13. - when a meteoroid enters Earth's atmosphere, friction with the air creates heat and produces this streak of light.
15. cloud - beyond the Kuiper belt.
17. - large rounds pits, caused by meteoroids, can be hundreds of kilometers across.
19. - planets begin to form as gravity pulled rock, ice, and gas together, the rock and ice formed small bodies called this.
23. - when an object spins around a central axis.
24. - a fuzzy outer layer formed by clouds of gas and dust.
25. - a thin disk of small particles of ice and rock.
26. - an Earth centered model.
27. - the force that attracts all objects towards each other.

1. - loose collections of ice, dust, and small rocky particles who's orbit can be very long, narrow ellipses.
2. - greek word for sphere
3. system - consist of the sun, the planets, their moons, and a variety of smaller objects.
4. belt - between Mars and Neptune.
5. - chunks of rocks or dust from space.
7. - greek word for sun
8. unit - average distance between Earth and the sun, about 150,000,000 kilometers.
10. - the solid inner core of a comet.
12. - round, orbit the sun, cleared out the region of the solar system along it orbit.
13. - hardened rock formed from huge lava flows, 3-4 billion years ago.
14. planets - what the inner planets are often called.
16. belt - beyond Neptune's orbit.
18. - a system in which Earth and the other planets revolve around the sun.
20. - meteoroids that pass through the atmosphere and are found on Earth's surface.
21. planet - an object that orbits the sun and has enough gravity to be spherical, but has not cleared the area of it's orbit.
22. - an oval shape.
26. house effect - trapping of heat by the atmosphere.
27. giants - what the four outer planets are called.