Earth’s Moon - 2

Virtually everyone can see the Moon, no matter where on Earth they are. Most people know that the Moon’s gravitational pull on the Earth causes our ocean tides. But did you know that missions to the Moon have discovered the existence of Moonquakes, as well as water ice hidden in the permanently shadowed craters at the lunar poles? The lunar samples brought back by Apollo astronauts have shed new light on how the Moon was formed—it is now thought that roughly 4.5 billion years ago, a rocky impactor about the size of Mars hit the young Earth. The debris scattered by that collision orbited the Earth briefly (only about a month!) before coalescing into the Moon. The Moon was further struck by a heavy bombardment of asteroids around 3.9 billion years ago, causing much of the cratering now seen. The dark blotches on the Earth-facing side of the Moon are lunar mare, essentially large, dark plains of basalt formed by volcanic eruptions


Why does the Moon have a reddish hue in these images of a lunar eclipse? It is the same reason that the Sun appears reddish during a sunset: scattered light. During a lunar eclipse, the Earth is situated directly between the Sun and the Moon. The only sunlight reaching the Moon travels through dense layers of Earth's atmosphere. Atmospheric particles preferentially scatter out shorter (bluer) wavelengths leaving only the longer (redder) wavelengths to refract (bend) through the atmosphere and illuminate the Moon.