The Sun-Earth-Moon System

Vocabulary flashcards covering key definitions and concepts related to the Sun-Earth-Moon system.

rotation

the spin of an object around its axis.

rotation axis

the line on which an object rotates.

orbit

the path an object follows as it moves around another object.

revolution

the orbit of one object around another object.

solstice

when Earth's rotation axis is tilted directly toward or away from the Sun.

equinox

when Earth's rotation axis is tilted neither toward nor away from the Sun.

phase

the lit part of the Moon or a planet that can be seen from Earth.

waxing phase

phases of the Moon during which more of the Moon's near side is lit each night.

waning phase

phases of the Moon during which less of the Moon's near side is lit each night.

umbra

the central, darker part of a shadow where light is totally blocked.

penumbra

the lighter part of a shadow where light is partially blocked.

solar eclipse

an occurrence during which the Moon's shadow appears on Earth's surface.