Moon phases 2024

The four principal phases

The Moon passes through four principal phases in about 29.5 days: new moon (Moon between Earth and Sun, unlit side towards us), first quarter (half the disc lit, on the right seen from the northern hemisphere), full moon (the whole disc lit) and last quarter (half lit, on the left). The days in between are crescent and gibbous, waxing before full moon and waning after it.

A lunar cycle lasts 29.53 days on average, but individual cycles range from about 29.3 to 29.8 days, so a year holds 12 or 13 of each principal phase, and the days between the four phases are not always the same.

Dates depend on the time zone

Each principal phase is one instant, the same everywhere. The calendar date of that instant depends on the time zone: a new moon at 23:30 UTC is already the next day in Asia and Australia. Use the switch above the calendar to read the dates in UTC or in your own zone; the grids and the lists change together.

The phase drawn for an ordinary day is the Moon at noon, so it is the same for everyone in that time zone. Illuminated percentages are the true lit fraction of the disc.

How we compute it

The principal phases are from Jean Meeus’s Astronomical Algorithms (chapter 49) and agree with the US Naval Observatory’s tables to the minute (checked for 2026 and 2027). The illuminated fraction comes from the Moon’s and Sun’s true positions. The calculation assumes a constant difference between Earth time and UTC and is good for 2000–2050.