Moon Phase

The Moon phase and illumination on any date, the Moon's age and the exact times of new and full moons in your time zone.

The Moon's phase is the same everywhere on Earth; the city only sets the time zone of the entered time and the answers.

Test yourself

The Moon phase calculator shows the phase and illuminated fraction of the Moon on any date and time, the Moon's age and the exact times of the nearest new and full moons in the chosen time zone.

Phases of the Moon

The Moon shines by reflected sunlight. Over a synodic month — 29.53 days on average — it goes through all phases: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, waning crescent.

The Moon's age is the number of days since the new moon. The illuminated fraction of the disk is approximately

k = ^{1 − cos(360° · t / T)}/₂

where t is the Moon's age and T the length of the synodic month. In the Northern Hemisphere the right side of a waxing Moon is lit, and the left side of a waning Moon.

New and full moon times are calculated with J. Meeus's algorithm, including corrections for the Moon's uneven motion — accurate to about a minute.