The Moon does not emit its own light, shining instead by reflecting sunlight. Depending on the relative positions of the Earth, Sun and Moon, varying amounts of the lunar surface appear to be illuminated.

A few days after the New Moon, a faint crescent appears that grows in size as the Moon approaches the First Quarter (position B in the diagram below). The waxing (growing) crescent Moon rises before noon, transits the meridian before sunset and sets before midnight. The waxing crescent phase repeats every 29.531 days – one synodic month.

The Moon’s motion around the Earth, with the Sun illuminating only one side of the Earth and Moon.