Waxing crescent Moon. The lunar phases arise as the Earth-Moon-Sun angle changes as the Moon orbits the Earth. This waxing crescent Moon is 4 days into its 28-day cycle. On a waxing Moon, the day-night line (terminator) marks the lunar dawn as sunlight advances over the Earth-facing side of the Moon. The Moon is crescent when it is less than half full. This image, published in 2015, uses data from the Lunar Reconnaissance Orbiter. The image is part of a sequence of lunar phases (see images C030/3708-3714), orientated for the northern hemisphere.