TWO YEARS IN TWO SECONDS: No two full Moons are exactly alike. To prove it, Laurent Laveder spent the last two years taking pictures of every full Moon over his home in France, and here is the result:

www.spaceweather.com/swpod2007/02may07/laveder_strip.gif

The Moon rocks and rolls, shrinks and swells, never presenting precisely the same face twice. "In the full-sized animation, you'll see 2 years condensed in only 2 seconds!" says Laveder. "Sorry for the mal de mer."

It shows the so-called libration of the moon, as also seen in this animation here.

The moon always shows the same side to us because its rotation is locked in synchrony with its orbit around the earth. However, there is still some relative movement during its month-long orbit, wobble, tilt, and zoom-in / zoom-out.

In the interval between full moons, the earth moves appreciably in its yearly orbit around the sun, so the full moons are a little out of synch with the lunar cycles -- each successive full moon catches the moon a little further ahead (or behind?) in its cycle. So when you view the successive full moons, you see the libration in much the same way that a flashing strobe can make a rapidly spinning wheel seem to turn slowly.