Unit 22

Terrestrial Planets

Rocky-surfaced, relatively small, dense inner planets closest to the Sun, including Mercury, Venus, Earth, and Mars.

Scarps

A line of cliffs produced by erosion or faulting.

Gas Giant Planets

Large, gaseous planets that are very cold at their surfaces; have ring systems, many moons, and lack 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 clouds that sink and flow rapidly in the Jovian atmosphere.

Zones

High, cool, light-colored clouds that rise and flow rapidly in the Jovian atmosphere.

Dwarf Planet

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

Meteoroid

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

Meteor

A streak of light produced when a meteoroid falls toward Earth and burns up in its atmosphere.

Meteorite

A small fragment of an orbiting body that has fallen to Earth, generating heat and possibly creating an impact crater.

Kuiper Belt

Region of space that lies outside the orbit of Neptune, 30 to 50 AU from the Sun, containing mostly rocky and icy small solar system bodies.

Comets

Small, eccentrically orbiting bodies made of rock and ice with 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.