Terminator or Terminus depending on how Latin you are.
terminator
Terminator
Far side
It's the line where part of the moon doesn't light the night. and, if you look, that line serves a purpose of telling what kind of moon night it is without looking at a calendar.
The two parts of the moon's shadow are the umbra, which is the dark central region where light is completely blocked, and the penumbra, which is the lighter outer region where only partial light is blocked.
the earth is between the moon and the sun. so that the solar light cant reach the moon that is in the earth's shadow, and becomes dark.
The fail of the fail spells failure...........
Dark.
the light areas of the moon are called the highlands. the dark areas are called maria.
The abrupt change (line) between light and dark on the moon is called the terminator. The shadow on the moon is there because the sun only lights up half of the moon (which is a sphere) at a time. Also, people on earth always see the same side of the moon. This is because the moon rotates at the same rate as it orbits (kinda tricky). This phenomenon is called tidal locking. The side of the moon we never see interestingly enough has the biggest impact crater in our solar system. So basically as the moon revolves around the earth and the terminator moves across the moon, more and more of the bright part is 'clipped away' until we eventually end up with a moon that looks totally black. This happens at the end of every month and is called the new moon. Here is the link to the wikipedia article. http://en.wikipedia.org/wiki/Lunar_phase
Half og the moon faces the sun and thus appears bright. Not always the same part, every part has its light and dark and there is no 'dark side' of the moon. Waxing and waining are changes in the parts of the moon where it is day.
The terminator is the line that separates "day" and "night" (the light and dark part of the Moon). It is interesting to note that close to the terminator, you can see more details, because of the shadows cast by mountains and craters.