Moon Phases

Today’s Moon, the next full and new Moons, and a calendar for the month.

Why the Moon has phases

Half of the Moon is always lit by the Sun. As the Moon orbits Earth, about once every 29.5 days, we see different amounts of the lit half. It is not Earth’s shadow. See Why does the Moon have phases? and the star map to see where the Moon is tonight.

Phases are calculated from the average length of the lunar month, so times of exact phases can be off by up to about half a day. Use an almanac for precise times.