satellite
a natural or artificial body that revolves around a celestial body that is greater in mass
moon
a celestial body that revolves around a body that is greater in mass; a natural satellite
mare
a large, dark are of basalt on the moon (plural, maria)
crater
a bowl-shaped depression that forms on the surface of an object when a falling body strikes the object's surface or when an explosion occurs
apogee
in the orbit of a satellite, the point that is farthest from Earth
perigee
in the orbit of a satellite, the point that is closest to Earth
eclipse
an event in which the shadow of one celestial body falls on another
solar eclipse
the passing of the moon between Earth and the sun; during a solar eclipse, the shadow of the moon falls on Earth
lunar eclipse
the passing of the moon through Earth's shadow at full moon
phase
the change in the illuminated area of one celestial body as seen from another celestial body; phases are caused by the changing positions of Earth, sun, and moon.
tide
the periodic rise and fall of the water level in the oceans and other large bodies of water
tidal range
the difference in levels of ocean water at high tide and low tide
tidal oscillation
the slow, rocking motion of ocean water that occurs as the tidal bulges move around the ocean basins
tidal current
the movement of water toward and away from the coast as a result of the rise and fall of the tides
rotation
the spin of a body on its axis
revolution
the motion of a body that travels around another body in space; one complete trip along an orbit
perihelion
in the orbit of a planet or other body in the solar system, the point that is closest to the sun
aphelion
in the orbit of a planet or other body in the solar system, the point that is farthest from the sun
equinox
the moment when the sun appears to cross the celestial equator
solstice
the point at which the sun if as far north or south of the equator as possible