Day and Night on the Moon

[P.H. Wise]

Does anyone know the day and night cycle on the moon? I am unfamiliar with the subject, but I would tend to think that days and nights followed the Lunar month as opposed to the twenty four hour cycle, but that's probably incorrect.

Anyone know what the actual numbers are for this?

[iiradned]

Day and night on the moon depends on where you are on the moon's surface.

The moon always keeps the same side facing the Earth. Thus if the moon is between the Earth and the Sun, the side facing Earth would be in lunar night and the side facing away from the Earth would be in lunar day.

This cycle lasts for a lunar orbit. Thus day and night follows the lunar month as you said.

[Knight of L-sama]

Basically as mentioned. The moon rotates about it's axis once for every time it orbits the earth, which takes approximately 28 days. As such a lunar day is going to be (appromiately) 14 terrestrial days of light followed by an equal length of darkness.

It might be worth point out the Peaks of Eternal Light and Valleys of Eternal Night. Near the moon's poles there are high mountains (especially around the south pole) that due to their height and the moon's tilt are almost perpetually in sunlight while near them are valley's that never recieve any sunlight for the same reason. The only time the Peaks of Eternal Light ever fall into shadow is during a lunar eclipse (which would appear on the moon as a solar eclipse).

[Drawde]

If I remember correctly, the change from light to dark is sudden. With no atmosphere, there's no twilight between night and day. I might be wrong on that though.

[Ellen Kuhfeld]

If I remember correctly, the change from light to dark is sudden. With no atmosphere, there's no twilight between night and day. I might be wrong on that though.

Yes and no. Twilight comes from scattered light, even after the direct light of the sun goes away. On Earth, the atmosphere does an effective job of scattering light. On the Moon, any mountains or hills in the vicinity would also scatter light. So on Earth, you have a fairly reliable twilight that changes with the weather and seasons. On the Moon, twilight depends on location and nearby topography.

And then there are Moonshine and Earthshine. But that's another matter.