A laser is a source of very intense, mono-chromatic and unidirectional beam of light. These properties of a leaser light can be exploited to measure long distances. The distance of the MOON from the Earth has been already determined very precisely using a laser as source of light. A laser light beamed at Moon takes 2.56 seconds to return after reflection at the the moon's surface.How much is the radius of the lunar orbit around the Earth?
