Word Finder - libration

definition

The act of librating.

definition

The apparent wobble or variation in the visible side of the Moon that permanently faces the Earth, allowing observers on Earth to see, over a period of time, slightly more than half of the lunar surface.

definition

(by extension) A similar rotational or orbital characteristic of some other celestial body.

definition

A vibrational degree of freedom whereby a group of atoms partly rotates back and forth, similar to the Moon's motion.

There is also a libration in latitude, arising from the fact that the axis of rotation of the moon is not precisely perpendicular to the plane of her orbit.

The capture clearly shows the libration spreading widening the signal (a clear tone would show up as a narrow line ).

If you would like to see a simulation of libration that really brings it to life then I recommend downloading Virtual Moon Atlas.

By De la Rue's advice, Pritchard began his career there with a determination of the physical libration of the moon, or the nutation of its axis.

His first important astronomical work was a careful investigation of the libration of the moon (Kosmographische Nachrichten, Nuremberg, 1750), and his chart of the full moon (published in 1775) was unsurpassed for half a century.

The other side of the moon is therefore invisible from the earth, but in consequence of the libration about six-tenths of the lunar surface may be seen at one time or another, while the remaining four-tenths are for ever hidden from our view.