Lunar eclipses are a spectacle, but they also have their scientific uses. Here is a photo
showing a red Moon and a green laser beam. The Moon's color tells you it's a total eclipse. The laser beam is aimed at a retroreflector left by Apollo 15 astronauts on the Moon in 1971. From the timing of the return light pulse, scientists can calculate the Earth-Moon distance to a high accuracy. The reflector performs better when the direct sunlight is blocked.