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 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.
The terminator.
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
The terminator
Because one side of the moon faces the Sun, whereas the other side of the moon faces away from the Sun and no other star is near to cast a significant amount of light on that surface. Furthermore, without an atmosphere to reflect and refract light, the line of demarcation between light and dark is very sharp. In addition, the rotation of the Moon is such that the same side always faces the Earth!
The line is called the terminator
terminator
Terminator
The terminator is the line - on any planet - between light and dark.... but it is rarely a 'line' in the true sense here on Earth, it's more of a zone.
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.
dark-line spectrum...
The terminator.
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
The terminator
Take a look at the color swatches at the beauty supply as each color line tends to run either a little dark or a little light. If the line runs dark, choose 6N and if it runs light, choose 5N for light brown results.
An illuminator is the line that seperates the light section on the earth and the moon from the dark sections.
grey line