Third Quarter Moon (at 00:38 GMT on Friday)

The moon will complete three quarters of its orbit around Earth, measured from the previous new moon, on Thursday, July 17 at 8:38 p.m. EDT or 5:38 p.m. PDT, which converts to Friday at 02:52 GMT. At the third (or last) quarter phase the moon appears half-illuminated on its western, sunward side. It will rise around midnight local time, and then remain visible until it sets in the western daytime sky in early afternoon. Third quarter moons are positioned ahead of the Earth in our trip around the Sun. About 3½ hours later, Earth will occupy that same location in space. The week of dark, moonless evening skies that follow this phase are the best ones for observing deep sky targets.