As one of the most prominent craters on the Moon, it is appropriate that Tycho should be named after one of astronomy's most prominent figures: Tycho Brahe, whose accurate observations in the 16th century provided the basis of Kepler's laws of planetary motion.

It boasts the largest ray system, which stretches over 1500 km and is curiously separated from the crater itself by a ring of dark material.

Photo: Patrice Poyet. The full size original of this can be seen in his large annotated collection of images, Poyet's Celestial HyperBook.

Inconstant Moon