For other worlds, we usually have to rely on other data: fluctuations in gravity, or the gentle rocking motion known as libration.
The authors of the new study used data from the Cassini probe orbiting Saturn to measure the libration of Mimas.
The one on the left illustrates the manner in which the libration in longitude is made apparent.
A list of some of the principal astronomical researches of Lagrange and Laplace:—libration of the moon.
The last of Galileo's great astronomical discoveries related to the libration of the moon.
We'd show enough, however, to make it damned impressive, and explain it by libration of the satellite.
The admirable memoir of Lagrange upon the libration of the moon seemed to have exhausted the subject.
But it is only an insignificant margin of the far side of the moon which this libration permits us to examine.
One more astronomical discovery also he was to make—that of the moon's libration.