Determine the moon phase, illumination percentage, and moon age for any date, with upcoming major phase dates.
How it works
This calculator uses the synodic month algorithm, measuring days elapsed since a known new moon reference and dividing by the 29.53-day lunar cycle.
Results are approximations. Actual phases can vary by up to a day due to orbital eccentricity and other perturbations.
Result
The moon is 8.8% illuminated, 2.83 days into the current lunar cycle.
Upcoming phases
Also in Calendar Reference
Dates & Time
Determine the current moon phase for any date, including illumination percentage, moon age, and upcoming major phase dates.
The calculator uses the synodic month (approximately 29.53 days) to compute how far through the lunar cycle a given date falls. From this moon age, it derives the phase name, illumination percentage, and dates of the next new moon, first quarter, full moon, and last quarter.
The lunar cycle is divided into eight phases: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, and Waning Crescent. Each phase lasts roughly 3.7 days.
Frequently asked questions
It uses a simplified synodic model accurate to within about a day for dates within a few centuries of the year 2000. For precise astronomical data, consult an ephemeris.
Moon age is the number of days since the last new moon, ranging from 0 to approximately 29.53 days.
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