| A | B |
|---|
| gas giant | outer planets |
| ring | thin disk of rock and ice that surrounds each of the gas giant planets |
| terrestrial planets | four inner planets |
| greenhouse effect | gases in the atmosphere that trap solar energy |
| comet | loose collection of ice, dust and rock wigth a long narrow orbit of the sun |
| coma | fuzzy outer layer of a comet |
| nucleus | solid inner core of a comet |
| Kuiper belt | region where comets originate; stretches from Pluto to 100 times Earth's distance from the sun |
| Oort cloud | spherical region of comets that surrounds the solar system |
| asteroid | rocky objects revolving around the sun; too small to be a planet |
| asteroid belt | region between the orbits of Mars and Jupiter where many asteroids are found |
| meteoroid | a chunk of rock in space |
| meteor | a meteoroid that is traveling through the atmosphere; a shooting star |
| meteorite | a meteor that hits the Earth's surface |
| extraterrestrial life | life that exiswts other than on Earth |
