GLY 1001 Earth Science

Chapter 22 Vocabulary

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1. Asteroid – thousands of small planet-like bodies, ranging in size from a few hundred kilometers to less than a kilometer, whose orbits are mainly between those of Mars and Jupiter.

Coma – The fuzzy, gaseous component of a comet’s head.

2. Comet - A small body that generally revolves around the Sun in an elongated orbit.

Escape velocity – The initial velocity an object needs to escape from the surface od a celestial body.

3. Inner planets - Any of the Earth-like planets, including Mercury, Venus, mars and Earth.

Iron meteorite – One of the three main categories of meteorites. This group is composed largely of iron with varying amounts of nickel (5-20%).Most meteorite finds are of this type.

4. Jovian planets – Jupiter-like planets: Jupiter, Uranus, Neptune, and Saturn which have very low densities.

5. Kuiper belt – A region outside the orbit of Neptune where most short-period comets are thought to originate.

Lunar highlands – The extensively cratered highlands of the Moon.

Lunar regolith – A thin gray layer on the surface of the Moon, consisting ofloosely compacted, fragmented material believed to have been formed by the repeated meteorite impacts.

Maria – The Latin name for the smooth areas of the Moon formerly thought to be seas.

6. Meteor – The luminous phenomenon observed when a meteoroid enters Earth’s atmosphere and burns up

7. Meteorite – Any portion of a meteoroid that survives the traverse through Earth’s atmosphere and strikes the Earth’s surface

8. Meteoroid - Small solid particles that have orbits in the solar system

Meteor shower – Many meteors appearing in the sky caused when Earth intercepts a swarm of meteoritic particles.

Oort cloud – A spherical shell composed of comets that orbit the Sun at distances generally greater than 10,000 times the Earth-Sun distance.

9. Outer planets – Jupiter-like planets: Jupiter, Uranus, Neptune, and Saturn which have very low densities.

Stony-iron meteorite – One of the three main categories of meteorites. This group, as the name implies, is a mixture of iron and silicate minerals.

Stony-meteorite – One of the three categories of meteorites. Such meteorites are composed largely ofsilicate minerals with inclusions of other minerals.

Terrae - The extensively cratered highlands of the Moon.

10. Terrestrial planet - Any of the Earth-like planets, including Mercury, Venus, mars and Earth.