NASA Pollution



A billion years ago, our Moon was closer to Earth than it is now. As a result, it appeared to be a much larger object in the sky. During that ancient era, if human beings had been around to witness such a sight, it would have been possible to see the entire Moon--not merely the one near side face that we see now. A billion years ago, it took our Moon only twenty days to orbit our planet, and Earth's own day was considerably shorter--only eighteen hours long. Stupendous, almost unimaginably enormous tides, that were more than a kilometer in height, would ebb and flow every few hours. However, things changed, as the lunar orbit around our primordial planet grew ever wider and wider. Annually, Earth's Moon moves about 1.6 inches farther out into space. Currently, the lunar rate of rotation, as well as the time it takes to circle our planet, are the same. Full moons on different days. Where you live on earth rarely makes a difference as to whether the moon is full, quarter or new. This is because it takes the moon almost a month to travel around the earth and it only takes a day for the earth to turn around once. So in comparison, the moon sort of sits in the sky and waits for us to see what phase it is in. Still, there are times when the moon will be full on different calendar days in different areas of the earth. Conventionalized images of the Man in the Moon seen in Western art usually display a simple "face" in the full Moon, or a human profile in the crescent Moon, that correspond to real topological features on the lunar surface.