Moon phase today

The phases

The Moon is always half lit by the Sun; what changes is how much of that lit half faces us. At new moon the Moon sits roughly between the Earth and the Sun and we see its dark side. Over the next week a growing waxing crescent appears in the evening sky until, at first quarter, the Moon is 90° from the Sun and half its disc is lit. The waxing gibbous moon then fills out to full moon, opposite the Sun, rising at sunset. Afterwards the sequence runs backwards — waning gibbous, last quarter, waning crescent — with the Moon rising later each night and finally showing only in the pre-dawn sky.

New moon, first quarter, full moon and last quarter are exact moments, not days. Calendars mark the day on which that moment falls, which is what this page does for your time zone; the other days take the name of the phase in between.

Why the cycle is 29.5 days

The Moon goes round the Earth in 27.3 days relative to the stars, but in that time the Earth has moved along its orbit, so the Moon needs about two more days to line up with the Sun again. The average time from one new moon to the next — the synodic month — is 29.53 days, but individual months vary between about 29.3 and 29.8 days because the Moon's orbit is elliptical.

How it is calculated

The page computes the positions of the Sun and Moon along the ecliptic using standard formulas from Jean Meeus's Astronomical Algorithms, keeping the largest terms of the lunar theory. The phase is the angle between them as seen from Earth; the illuminated fraction follows from that angle. All of it runs in your browser.

Questions and answers

When is the next full moon?

The list of upcoming phases on this page gives the exact moment of the next full moon converted to your time zone. Full moons come every 29.5 days on average, so there are usually twelve in a year and occasionally thirteen.

Why does the full moon fall on different dates in different countries?

The full moon is a single instant, the moment the Moon is opposite the Sun. If that instant is 04:12 UTC, it is the 26th in London and New York but still the evening of the 25th in Los Angeles, so calendars printed for different time zones show different dates.

What does “illumination” mean?

The fraction of the Moon's visible disc lit by the Sun, from 0% at new moon to 100% at full moon. It changes slowly near full and new moon and fastest near the quarters, so the Moon can look full for a couple of nights.

What is the moon's age?

The number of days since the last new moon. It runs from 0 to about 29.5, and the phases follow it: first quarter near day 7.4, full near day 14.8, last quarter near day 22.1.

What is a blue moon?

Either the second full moon in a calendar month, or the third of four full moons in an astronomical season. Both happen about every two to three years. It has nothing to do with colour.

How accurate is the phase timing?

We compared the calculated times of all 99 principal phases in 2026 and 2027 with the U.S. Naval Observatory's tables: none was off by more than 20 minutes. That is precise enough to name the phase of each day correctly except when a phase falls within minutes of midnight.

Sunrise and sunset for your city are on the sunrise and sunset page.