During the first days of the lunar cycle, the Sun illuminates a small section of the Moon, rendering it both visible and clear. At the same time, the Sun lights up the Earth, which in turn reflects its light onto the Moon. This faint sunlight, bounced off the Earth, allows the dark portion of the Moon to be only subtly discernible – this is earthshine.

This series of photographs shows, over five consecutive days, a duality: the part of the Moon lit directly by the Sun and the part aglow with the light reflected from the Earth. At first glance, this phenomenon is not always readily observable. Today, the measurement of earthshine is employed to monitor terrestrial climate change.