Lunar Libration
or "Why Every Full Moon is Unique"

In school we learned that one side of the Moon always faces Earth, and we can never see the other side. That's true, but only approximately. Consider the following: Photographer Laurent Laveder spent the last two years taking pictures of every full Moon over his home in France, and he assembled the images into a time-lapse movie.

The Moon rocks and rolls, shrinks and swells, never presenting precisely the same face twice. "This is 2 years condensed in only 2 seconds!" says Laveder. "Sorry for the mal de mer."

Because the Moon's orbit is slightly elliptical (5%) and slightly tilted (5°), we view each month's full Moon from a slightly different distance and angle. This makes each full Moon unique. The rocking motions are called libration; because of libration we can observe not just 50% but rather 59% of the Moon's surface.

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