The moon phase on a specific date is the Moon’s phase, illumination and age at 12:00 UTC on that day, which the date picker above shows for any day from 1900 to 2100. Each date has its own page with the Moon’s distance, zodiac sign, the nearest new, quarter and full moons, and a link to that month’s calendar.
How do you look up the moon phase for a date?
Choose a day in the date picker and the tool opens that date’s page, at an address such as /moon-phase/1969-07-20/. Each date page shows:
- Phase name: the primary phase (New Moon, First Quarter, Full Moon or Last Quarter) when its exact instant falls inside that UTC day, otherwise the in-between phase at 12:00 UTC.
- Illumination: the percentage of the Moon’s visible disc that is sunlit at 12:00 UTC.
- Age: the days since the previous new moon.
- Distance: the distance from Earth’s center to the Moon’s center in kilometers and miles.
- Zodiac sign: the tropical sign the Moon is passing through.
- Nearest primary phases: the new, quarter and full moons before and after the date, with exact UTC times.
For the Moon at this moment, drawn for your own sky with local rise and set times, use the live moon phase today page instead.
Why does the lookup use 12:00 UTC?
The lookup uses 12:00 UTC so that every date has one fixed answer worldwide, taken at the middle of the UTC day. The Moon changes continuously, however, and the calendar date of any moment depends on your time zone.
A full moon at 02:00 UTC is still the previous evening in New York and Los Angeles, so a calendar made for the Americas lists it one day earlier than a calendar made for Europe. Apollo 11 shows the same effect: Neil Armstrong’s first step on the Moon came at 02:56 UTC on July 21, 1969, which was 10:56 p.m. on July 20 in New York.
The phase name follows the UTC date. A date page is named after a primary phase only when that phase’s exact instant falls between 00:00 and 24:00 UTC on that date. When your local date and time matter, as they do for a birth, use a tool that takes your time zone into account.
How far back and forward can you check, and how accurate is it?
The lookup covers every day from January 1, 1900, to December 31, 2100, calculated with Astronomy Engine, which places the Moon to within about 1 arcminute. Over that range, the main source of uncertainty is not the Moon’s orbit but Earth’s rotation.
Astronomical positions are calculated on a uniform time scale, and converting them to clock time needs a correction called ΔT (delta T): the gap between that uniform time and time kept by Earth’s slightly irregular spin. ΔT was close to zero in 1902 and about 64 seconds in 2000. For future dates it has to be extrapolated, and NASA notes that the uncertainty grows the further ahead the prediction goes. The engine uses the Espenak–Meeus formula published by NASA.
Across 1900–2100 that uncertainty amounts to seconds or minutes, not hours. It can only change a date’s phase name when a primary phase falls within moments of midnight UTC.
Which famous dates can you check?
Famous dates are a quick way to see how the lookup works. Each link opens the date page, which shows the phase for that day.
| Date | Event | Date page |
|---|---|---|
| July 20, 1969 | Apollo 11’s lunar module Eagle lands at 20:17 UTC | Moon phase on July 20, 1969 |
| July 21, 1969 | Neil Armstrong’s first step, 02:56 UTC | Moon phase on July 21, 1969 |
| December 11, 1972 | Apollo 17 lands, the last of six crewed Moon landings | Moon phase on December 11, 1972 |
| January 1, 2000 | The first day of the year 2000 | Moon phase on January 1, 2000 |
| January 1, 1900 | The first date the lookup covers | Moon phase on January 1, 1900 |
The two Apollo 11 dates show the time zone effect in practice. The landing and the first step were about six and a half hours apart, yet they fall on different UTC dates.
What do people use a moon date lookup for?
People use a date lookup to put a known day into lunar context, from a birth or a wedding to a historical event or an entry in a fishing log.
- Birthdays: the moon phase on your birthday tool adds an optional birth time and time zone and gives a result you can share.
- Weddings and events: check whether a past wedding fell on a full moon, or pick a date with a bright Moon in the evening sky for an outdoor event.
- Historical research: check whether a night described as moonlit in a letter, diary or report could have been, or how much moonlight there was on a given date.
- Fishing and hunting logs: anglers and hunters who record outings by date can add the phase to look for patterns over several seasons.
To see a whole month or year at once, the moon phase calendar lays out every day with its phase and the exact time of each primary phase.