Moon Key Terms
Terms in this set (32)
Something that refers to Earth's moon.
The imaginary line that passes through the center of an object and around which it spins.
Spinning around an axis (refers to the motion of only one object!). Ex "The Earth's rotation on its axis takes about 24 hours".
One object moving around another object in a circular motion (refers to two objects). Ex "The Earth's revolution around the Sun takes 365.25 days".
The half of the Moon that always faces away from Earth.
The half of the Moon that always faces towards the Earth.
The lunar 'soil' (fine dust and rock).
Dark, flat areas formed from ancient lava flows.
Large round pits caused by the impact of space objects.
Light colored, ridge-like structures.
The different shapes of the near side of the Moon as seen from Earth.
A moon phase that cannot be seen. The half of the Moon reflecting sunlight is facing away from Earth (the Moon is between the Sun and Earth).
1st Quarter Moon
The Moon appears as half of a circle; the right side is rounded (the moon is 1/4 of the way in its revolution around Earth).
The Moon appears as a complete circle; the entire near side is reflecting light towards Earth (Earth is between the Sun and the Moon).
3rd/Last Quarter Moon
The Moon appears as half of a circle; the left side is rounded (the moon is 3/4 of the way around its revolution of Earth).
A "sliver" of Moon that occurs during the week before and the week after a New Moon.
A Moon phase that is almost but not quite full. It occurs in the week before and the week after the full moon.
Moon phases that appear to be growing larger each night (from New to Full Moon).
Moon phases that appear to be growing smaller each night (from Full to New Moon).
The Moon's Sidereal Period
The time it takes the Moon to revolve 360° around the Earth; 27.3 days.
The Moon's Synodic Period
The time it takes the Moon to orbit around the Earth relative to the Sun (Sun-Earth-Moon lined up or, New Moon to the following New Moon); 29.5 days (about 1 month). Because the Earth continues moving in its orbit around the Sun, after the Moon has gone 360° around the Earth, it takes a bit more time for it to once again line up with the Earth and Sun (a.k.a. "lunar month")
The Moon Phase Cycle
The time it takes the Moon to pass from one New Moon phase to the next (29.5 days).
When it takes the same amount of time for something to orbit an object as to rotate on its axis. The Moon spins at the same speed as it orbits the Earth. It takes the Moon 27.3 days to orbit the Earth; it also takes the Moon 27.3 days to rotate/spin once on its axis (this is why we see only one side of the Moon!).
An imaginary plane on which the Earth orbits around the Sun or the Moon orbits around the Earth. The orbital plane of the Moon is tilted compared to the orbital plane of the Earth.
One object orbiting directly around another. The Moon is a natural satellite of the Earth.
When either the Moon or the Earth falls into the shadow of the other.
When the Moon passes in front of the Sun and casts a shadow on the Earth.
When the Moon passes behind the Earth and travels through the Earth's shadow.
The dark, inner shadow of an eclipse.
The lighter, outer shadow of an eclipse.
An eclipse in which the Moon/Earth passes into the umbra of the other.
An eclipse in which only part of the Moon/Earth passes into the umbra of the other.