Moon Phases

Moon phase dates for the months ahead

The next full Moon is Sat, September 26, 2026 and the next new Moon is Fri, September 11, 2026, in Universal Time. Every instant below is computed with the standard lunation series (Meeus, Astronomical Algorithms, ch. 49) and stated in UTC; your local calendar can shift a date by one day, and the omitted fine terms cost a few minutes at most.

For the Moon’s sign changes and void-of-course hours in the four days ahead, measured to the hour, see the Void-of-Course Moon Calendar.

The eight familiar phase names

The common sequence is new Moon, waxing crescent, first quarter, waxing gibbous, full Moon, waning gibbous, last or third quarter, and waning crescent. These labels divide a continuous cycle into useful neighborhoods. Only new, first quarter, full, and last quarter describe exact geometric event moments in standard almanacs; the crescent and gibbous phases fill the intervals.

Why the Moon changes shape

Sunlight always illuminates roughly half of the Moon. From Earth, the fraction of that lit hemisphere we can see changes as the angle among Sun, Earth, and Moon changes. Near new Moon the lit side mostly faces away from us. Near full Moon the lit side mostly faces Earth. The terminator (the boundary between lunar day and night) reveals relief especially well through binoculars or a telescope.

Phase, age, and illumination are different

Lunar age counts time since new Moon, phase names describe parts of the cycle, and illuminated fraction estimates how much of the visible disk is sunlit. They correlate but are not interchangeable. A broad phase family derived from longitude is useful for orientation; precise illumination and exact event timing come from a lunar ephemeris that accounts for the Moon’s real orbit.

Phase does not supply a local schedule

The full Moon generally rises near sunset and a new Moon travels near the Sun, but exact rise and set times change with location and date. Twilight definitions, refraction, the observer’s horizon, and the Moon’s changing declination all matter. Use a location-aware table rather than adding a fixed number of minutes to yesterday’s time.

How to use a phase calendar responsibly

A phase calendar is excellent for planning moonlight-sensitive observing, photography, or a simple nature journal. It is not a substitute for a local visibility forecast. If you also use lunar phases symbolically, label that practice as reflection or tradition. Claims about medical outcomes, emergencies, markets, or human behavior require evidence beyond the calendar.