The sub-Earth point gives the amount of libration in longitude and latitude. The word comes from the Latin for 'balance scale' (as does the name of the zodiac constellation Libra) and refers to the way such a scale tips up and down on alternating sides.

When a month is compressed into 24 seconds, as it is in this animation, our changing view of the Moon makes it look like it's wobbling.

Because of the tilt and shape of its orbit, we see the Moon from slightly different angles over the course of a month. The Moon always keeps the same face to us, but not exactly the same face. The pummeled, craggy landscape thrown into high relief at the terminator would be impossible to recreate in the computer without global terrain maps like those from LRO. This is especially evident in the long shadows cast near the terminator, or day-night line. Its laser altimeter ( LOLA) and camera ( LROC) are recording the rugged, airless lunar terrain in exceptional detail, making it possible to visualize the Moon with unprecedented fidelity. Lunar Reconnaissance Orbiter ( LRO) has been in orbit around the Moon since the summer of 2009. Until the end of 2021, the initial Dial-A-Moon image will be the frame from this animation for the current hour. The animation archived on this page shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2021, at hourly intervals. The data in the table for the entire year can be downloaded as a JSON file or as a text file. Hover over the image to reveal the animation frame number, which can be used to locate and download the corresponding frame from any of the animations on this page, including unlabeled high-resolution Moon images. See also the Dial-A-Moon for the May 26 total lunar eclipse.Ĭlick on the image to download a high-resolution version with feature labels and additional graphics.

Libra scale sketch