Equator
imaginary line that divides the earth into northern and southern hemispheres
Equinox
day when Earth's axis is not leaning toward or away from the Sun
orbit
The path an object follows as it moves around another object
revolution
motion of an object around another object
Rotation
The spinning motion of a planet on its axis
rotation axis
the line on which an object rotates
solstice
a day when Earth's rotation axis is the most toward or away from the Sun
maria
the large, dark, flat areas on the Moon
phase
the lit part of the Moon or a planet that can be seen from Earth
waning phase
occurs when less of the Moon's near side is lit each night
waxing phase
occurs when more of the Moon's near side is lit each night
lunar eclipse
occurs when the Moon moves into Earth's shadow
penumbra
the lighter part of a shadow where light is partially blocked
solar eclipse
occurs when the Moon's shadow appears on Earth's surface
tide
the daily rise and fall of sea level
umbra
the central, darker part of a shadow where light is totally blocked
neap tide
a tide just after the first or third quarters of the moon when there is the least difference between high and low water.
spring tide
a tide just after a new or full moon, when there is the greatest difference between high and low water.
gibbous moon
when the size of the illuminated portion of the moon is greater than half but not a full moon,
lasts about 6 days can be almost all white or just a little more than 1/2 white