Re: Is it possible to walk from the lighted side to the dark side of the moon?

Good question!

The Moon's "day" is about 29.5 days long, so the sun moves very slowly across the lunar sky. The moon is also much smaller than the Earth, with a circumference of only 10,000 km at the equator. Exact numbers can be found in this other answer.

So at the equator the terminator line is moving about 9.5 miles per hour. A fast runner could overtake the terminator line for short periods of time at the equator, but probably couldn't keep up for long. Still, 9.5 miles per hour is a lot slower than the 1000 miles per hour that the terminator moves on Earth!

But that's just the number for the moon's equator; if you were closer to the lunar poles, then the terminator would move even slower than 9.5 miles per hour. If you were far enough north or south, you might even be able to walk all the way around the moon, staying in sunlight the whole time. (A famous science fiction short story, called "A Walk in the Sun" by Geoffrey Landis, uses this idea.)

Of course, even if you weren't moving at all, the terminator would pass over you twice every 29.5 days; once going from night to day, and once going from day to night.

As for the changes you would see, a sunset on the moon would look very different from a sunset on Earth because there's no atmosphere to scatter the sunlight. Either you're in a direct line-of-sight to the sun (in which case it's bright), or no sunlight can reach you (in which case it's dark.) There's not a lot of gray area, so to speak.

However, that doesn't mean that the terminator will appear as a straight line, becuase the moon has mountains and craters which will cast funny shadows. Here's a picture of a crater showing just how complicated the line between day and night can be.

Another big change is the temperature. The moon can get very hot and cold, depending on whether it is day or night. (The surface temperature extremes can get up to 127 C in the daytime and down to -173 C at night.)

Hope that answers most of your questions...