Solve and annotate any Moon image

It solves a photo of the Moon blind, the way SkySolver solves star photos: with no date, scale or orientation given, it finds where the Moon's disk lies in the frame, which way its north points, whether the image is mirrored, the libration and the direction of the Sun, and from it the phase. From then on every pixel has its selenographic longitude and latitude, and 6,971 named features of the near side are drawn on the photo. Lunar tools such as MoonView or LTVT can label a photo only once you have marked known craters by hand or entered when and where it was taken; SkySolver needs the photo alone.

The whole disk at any phase, crescents (best with a little earthshine), a small Moon above a landscape or in a daylight sky, and telescope close-ups of a region, in colour or black and white, mirrored or not. The disk can be small: on a clear sky about 3 % of the frame's width is enough.

Mostly in the size of the field. Of 201 telescope close-ups gathered from the web it verifies nine in ten; the ones it misses are tight fields along the terminator, a few hundred kilometres across or less. On test fields cut from sharp photos it solves about four in five at 250-350 km (a mare, Clavius with its surroundings), two in three at 180 km, and one in three at 60-130 km, a single mid-sized crater filling the frame. Framing a crater with some of its surroundings helps more than a sharper photo. Where it cannot place a field it answers “unsure” rather than guess: none of several hundred photos of other things was taken for the Moon. The far side is not covered, and very blurred photos and the thinnest crescents without earthshine can still fail. A solve takes a second or two; a photo it cannot place, up to about ten.

No. The phase and the libration are read from the photo itself.

The limb and the terminator, a selenographic grid, the maria with their real outlines, the craters, mountains, valleys and rilles by name and to size, the relief from NASA's LOLA laser altimeter, and the Moon as a globe with your photo's frame on it. Point at any feature for its kind, size and position. You can download the annotated photo, the annotation as PNG or SVG, the features in the frame as CSV and the solution as JSON.

No. The solver gets a greyscale copy at most 2048 pixels across, solves it in memory and forgets it as soon as it has answered. Nothing is stored or logged.

Yes, with the API: send the photo and get back the disk, the libration, the Sun, the phase and where each corner of the frame lies on the Moon. Free, no key.

Those go to SkySolver's star solver: it finds where any night-sky photo points, from a telescope frame to a 360° panorama, usually in milliseconds, and labels its constellations, nebulae and galaxies. Solve a star photo.