bild

1 day old moon with earthshine, optical image. This waxing (increasing in apparent size) moon has a crescent sliver of sunlight highlighting its underside. The rest of the surface is faintly lit by light reflected from the Earth, a phenomenon known as earthshine. The moon here is in its first day of a 28-day cycle. (KEYSTONE/SCIENCE PHOTO LIBRARY/ECKHARD SLAWIK)