Earth-Moon-Sun System Key Terms

Apogee

Point in the Moon's orbit when it is furthest from the Earth

Satellite

Any object that moves around another object

Star

Self-illuminated body in space made of glowing hot gases heated by nuclear fusion in its core

Moon

A natural object in space that orbits a planet

Revolution

Movement of an object around some point or other object in space; process of orbiting

Ellipse

Oval -shaped

Orbit

Elliptical path in which an object in space moves around another object in space

Astronomy

Study of the universe outside of Earth and its atmosphere

Planet

Nearly round object in space that dominates its orbit around a star

Rotation

Turning or spinning of an object about an axis

Sun

The closest star to earth and the center of our solar system

Perigee

Point in the Moon's orbit when it is closest to the Earth

Phases of the Moon

The various shapes of the lit portion of the moon seen from earth as it travels in its orbit around earth; the change in the appearance of the moon as seen from earth as it orbits earth

Spring Tides

Tides with a larger difference between successive high and low tides that occur during the full and new moon phases

Waxing

Growing larger, increasing

Lunar Eclipse

Blocking out of the moon by earth that occurs when the earth moves directly between the sun and the moon; the earth casts its shadow on the moon

Neap Tides

Tides with a smaller difference between successive high and low tides that occur during the quarter phases of the moon

Ecliptic

Plane in which the earth's orbit around the sun lays

Waning

Growing smaller, decreasing

Tides

Daily changes in the elevation of the ocean surface

Solar Eclipse

Blocking out of the sun by the moon that occurs when the new moon moves directly between the earth and the sun; the moon casts its shadow on earth

Solstice

The two days throughout the year in which the sun stops getting higher or lower in the sky at midday

Equinox

The two days throughout the year in which the length of day is equal to the length of night everywhere on Earth