Third Quarter Moon (at 11:59 GMT)

The moon will reach its third quarter phase on Tuesday, May 20 at 7:59 a.m. EDT, 4:59 a.m. PDT, and 11:59 GMT. Third quarter moons always rise around midnight in your local time zone and then linger into the southern sky after sunrise. At third, or last, quarter, the moon’s western half is illuminated by the pre-dawn sun and the pole-to-pole terminator line becomes a straight line. The week of dark, moonless evening skies that follow this phase will be ideal for observing deep sky targets in binoculars and telescopes, especially spring galaxies.