Earthshine is sunlight which is reflected by the Earth and illuminates the Moon’s night side.The overexposed part of the Moon is the part illuminated by direct sunlight, the other darker part is illuminated indirectly by sunlight reflected by the Earth.

Earthshine is most easily observed when the Moon is new (as viewed from Earth).

Earthshine can be caught photographically by using a somewhat longer exposure time to reveal the shadow side, this however always burns out the light part of the Moon. (at least in the pre-HDR era…)