Almost everyone has heard it but almost no one has seen it.

Now you can do both.

Pink Floyd released The Dark Side of the Moon in 1973. The album has since been re-released in a variety of formats, has sold tens of millions of copies, and is routinely cited as one of the most influential albums of all time.

Last week NASA’s Scientific Visualization Studio released a video that shines a light on the moon’s dark side. Like the side of the moon we see, the far side goes through a series of phases which are shown in the video.  The highly detailed and accurate images of the moon seen in the video were created from data returned by the  Lunar Reconnaissance Orbiter which launched in 2009.

Why do we only see one side of the moon? In a word, gravity. Because they are large masses in relatively close proximity, the earth and the moon each exert a gravitational pull on the other. The moon’s gravitational pull produces the tides. The earth’s gravitational pull has slowed the rotational speed of the moon to the point where it takes 29.5 days to revolve once on its axis which is the same time it takes to orbit around the earth. The result is that only one side of the moon is visible from the surface of the earth.