tycho

Around the time of the full moon, Tycho's ray system is illuminated to best effect, and can be traced nearly 1000 miles across the lunar surface. When the Moon is a thin crescent, the light reflected from the Earth (which would appear full as seen from the Moon) creates a similar - but fainter - illumination, and some of the stronger rays can be seen on the dark part of the Moon's disc.

Photo: António Cidadão. His Home Page of Astrophotography includes stereograms, animations, and "Seven Craters a Week" from his forthcoming photographic lunar atlas.

Inconstant Moon