13.6: Key Terms
- Page ID
- 66567
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- asteroid
- a stony or metallic object orbiting the Sun that is smaller than a planet but that shows no evidence of an atmosphere or of other types of activity associated with comets
- asteroid belt
- the region of the solar system between the orbits of Mars and Jupiter in which most asteroids are located; the main belt, where the orbits are generally the most stable, extends from 2.2 to 3.3 AU from the Sun
- comet
- a small body of icy and dusty matter that revolves about the Sun; when a comet comes near the Sun, some of its material vaporizes, forming a large head of tenuous gas and often a tail
- Kuiper belt
- a region of space beyond Neptune that is dynamically stable (like the asteroid belt); the source region for most short-period comets
- near-Earth asteroid (NEA)
- an Earth-approaching asteroid, one whose orbit could bring it on a collision course with our planet
- near-Earth object (NEO)
- a comet or asteroid whose path intersects the orbit of Earth
- nucleus (of a comet)
- the solid chunk of ice and dust in the head of a comet
- Oort cloud
- the large spherical region around the Sun from which most “new” comets come; a reservoir of objects with aphelia at about 50,000 AU
- tail
- (of a comet) a tail consisting of two parts: the dust tail is made of dust loosened by the sublimation of ice in a comet that is then pushed by photons from the Sun into a curved stream; the ion tail is a stream of ionized particles evaporated from a comet and then swept away from the Sun by the solar wind