The tool shows the Moon as it is right now: its phase, the share of its face that is lit, its age in days since the new moon, the sign it is in, the moment it moves into the next sign, and the dates and times of the next new moon, first quarter, full moon and last quarter, in your time zone. Pick another date to see the Moon at noon that day.
How it works
The Sun’s and the Moon’s positions come from NASA JPL DE440 data. The phase depends on one angle, the Moon’s elongation: how far ahead of the Sun it is along the zodiac. At 0 degrees it is a new moon, at 90 degrees the first quarter, at 180 degrees the full moon and at 270 degrees the last quarter. In between it is a crescent or a gibbous Moon, waxing before the full moon and waning after it.
The lit share is worked out from the same angle: (1 minus the cosine of the elongation) divided by two. It is the method our Moon phase on your birthday tool uses, and it agrees with a calculation that also allows for the Moon’s tilt to within about a fifth of a percentage point.
The Moon changes sign every two to two and a half days. The moment of each change was found when our data files were built, in the tropical zodiac that Western astrology uses.
Reading the result
The first line gives the phase and the sign together, for example a waning crescent in Virgo. The four principal phases are single moments, not whole days. If one of them falls on the date you chose, the tool names it and gives its exact time; on other days it names the crescent or gibbous phase.
The age counts days from the last new moon, from 0 at the new moon to about 29.5 just before the next. The sign card says when the Moon moves on, which is useful if you follow the Moon’s sign for the mood of the day.
Where traditions differ
The phase is pure astronomy and is the same in every tradition. The sign is not. Western astrology uses the tropical zodiac, measured from the March equinox, which is what this page shows. Vedic astrology measures the Moon against the stars, so its Moon sign, the rashi, is usually one sign earlier; the both systems tool shows the two side by side. Calendars also differ by a day on when to mark a full or new moon when the exact moment falls near midnight, because they use different time zones.
What it does not do
It does not give moonrise or moonset times, and it does not read the phase as a forecast. Dates run from February 1899 to November 2075, the range of our planet data.
Frequently asked questions
↳ Is the Moon phase the same everywhere?
Yes. Everyone on Earth sees the same phase at the same moment. The date and clock time differ with the time zone, which is why the tool uses your place or your device's time zone.
↳ How long does the Moon stay in one sign?
Between about two and two and a half days. The tool shows the moment it entered its current sign and the moment it leaves.
↳ Why is the full moon a moment and not a day?
The full moon is the instant the Moon stands exactly opposite the Sun. The Moon looks nearly full for a day or two around it, but the exact moment falls at one time, which the tool gives to the minute.
↳ What is the age of the Moon?
It is the time since the last new moon, in days. It runs from 0 at the new moon to about 14.8 at the full moon and about 29.5 just before the next new moon.
↳ Is today's Moon sign the same as my Moon sign?
No. Your Moon sign is where the Moon was when you were born. Today's Moon sign is where it is now. To find yours, use the Sun, Moon and Rising calculator.