Unit 22

Terrestrial Planets- rocky-surfaced, relatively small, dense inner planets closest to the Sun-Mercury, Venus, Earth, and Mars.

Scarps- A line of cliffs produced by erosion or faulting.

Gas Giant Planets- Large, gaseous planet that is very cold at its surface; has ring systems, many moons, and lacks solid surfaces- Jupiter, Saturn, Uranus, and Neptune.

Liquid Metallic Hydrogen- form of hydrogen with both liquid and metallic properties that exists as a layer in the Jovian atmosphere.

Belts- low, warm, dark-colored cloud that sinks and flows rapidly in the Jovian atmosphere.

Zones- high, cool, light-colored cloud that rises and flows rapidly in the Jovian atmosphere.

Dwarf Planet- an object that, due to its own gravity, is spherical in shape, orbits the Sun, is not a satellite, and has not cleared the area of its orbit of smaller debris.

Meteoroid- piece of interplanetary material that falls toward Earth and enters its atmosphere.

Meteor- streak of light produced when a meteoroid falls toward Earth and burns up in Earth’s atmosphere.

Meteorite- a small fragment of an orbiting body that has fallen to Earth, generating heat; does not completely burn up in Earth’s atmosphere and strikes Earth’s surface, sometimes causing an impact crater.

Kuiper Belt- region of space that lies outside the orbit of Neptune, 30 to 50 AU from the Sun, where small solar system bodies that are mostly rock and ice probably formed.

Comets- small, eccentrically orbiting body made of rock and ice which have one or more tails that point away from the Sun.

Meteor Shower- occurs when Earth intersects a cometary orbit and comet particles burn up as they enter Earth’s upper atmosphere.