Chapter 20Sections 1-3By: Shannon Harris

Astronomical UnitThe average distance between

the earth and the sun.

Terrestrial PlanetsThe name for the inner planets

Prograde RotationThe counterclockwise spin of a

planet or moon as seen from above the planet’s.

Retrograde RotationThe clockwise spin of a planet or

moon as seen from above planet’s.

Gas GiantsVery large planets that don’t

have any known solid surfaces.

Satellites Natural or artificial bodies that

revolve around larger bodies like planets.

Phases The different appearances of the

moon due to its changing position.

Eclipse Occurs when the shadow of one

celestial body falls on another.

Comet A small body of ice, rock, and

cosmic dust loosely packed together.

Asteroid Small, rocky bodies in orbit

around the sun.

Asteroid BeltA region of the solar system

between the orbit of Mars and Jupiter.

Meteoroid A small body moving in the solar

system that would become a meteor