First Quarter Moon

The moon will complete the first quarter of its 29.53-day trip around Earth on Sunday, December 8 at 10:27 a.m. EST, 7:27 a.m. PST, and 15:27 GMT. At first quarter, the moon’s 90-degree angle from the sun causes us to see it half-illuminated on its eastern side. First quarter moons always rise around mid-day and set around midnight, so they are also visible in the afternoon daytime sky. The evenings surrounding first quarter are the best ones for seeing the lunar terrain when it is dramatically lit by low-angled sunlight, especially along the terminator, the pole-to-pole boundary that separates the moon’s lit and dark hemispheres.