Moon Phase Calendar

Reading the Moon

The Moon makes no light of its own; we only ever see the half the Sun is lighting. As the Moon circles Earth once every 29.5 days (the synodic month), the angle between the Sun, Earth and Moon changes, so a different slice of that lit half faces us. That slow change is the cycle of phases, and the calendar above draws each day at the exact shape the Moon shows on that date. The full geometry, with a synced orbit-and-globe view, is on the Moon Phases lesson.

The four principal phases

Four moments anchor the cycle. At the new moon the Moon sits between us and the Sun and its lit side faces away, so it is invisible. About a week later the first quarter shows a half disk lit on the right. At the full moon the Moon is opposite the Sun and fully lit. Another week on, the last quarter is a half disk lit on the left. Between them the Moon is a crescent or gibbous, waxing (growing) on the way to full and waning (shrinking) on the way back to new. From the Southern Hemisphere the whole picture is rotated: the waxing moon fills from the left instead.

Full moon names and the blue moon

Each month's full moon carries an old almanac name drawn from the seasons: the Wolf Moon of deep winter, the Strawberry Moon of June, the Harvest Moon near the autumn equinox. Because 29.5 days is a touch shorter than most calendar months, now and then a single month holds two full moons; the second is the famous blue moon, which is not really blue. Eclipses are the special case where a new or full moon lands on a lunar node, which you can chase on the Eclipse & Saros Explorer.

The 19-year Metonic cycle

Stack 235 lunar months end to end and they come out almost exactly 19 years, missing by only about two hours. The Greek astronomer Meton built a calendar on this in 432 BC, and it is still the reason a given moon phase falls on nearly the same date 19 years apart, and why the date of Easter and the Hebrew calendar follow a 19-year rhythm. The small leftover drift is mopped up by the 76-year Callippic cycle. The calculator above lets you watch any date's Moon return almost unchanged across a lifetime. You can place this cycle among the sky's other rhythms on the Cycles by Length page.

See more of tonight's sky

For where the planets are and what is visible right now, open Today in the Sky, and to find your local sunrise, sunset and twilight times, use the day-length calculator.

Frequently asked questions

What is the moon phase tonight?

On September 21, 2026 (UTC) the Moon is a waxing gibbous, about 78% lit and waxing (growing), 10.1 days into its 29.5-day cycle. The CycleCalcs card at the top of this page draws tonight's phase at the Moon's true illuminated shape; with JavaScript on it recomputes live in your browser.

When is the next full moon?

The next full moon is September 26, 2026 at 16:49 UTC: the Harvest Moon, named for the moonlit evenings that let the harvest run late; properly, the full moon nearest the September equinox. The calendar on this page marks every full moon from 1700 to 2200, with each month's traditional name.

When is the next new moon?

The next new moon is October 10, 2026 at 15:50 UTC. New moon nights are the darkest of the month and the best for stargazing, because the Moon is beside the Sun in the sky and its lit side faces away from Earth.

Is there a lunar eclipse (blood moon) tonight?

No, not tonight. The next lunar eclipse is a penumbral eclipse on February 20, 2027 (UTC). Only a total lunar eclipse turns the whole Moon the copper red popularly called a blood moon; the Moon at the top of this page shows an eclipse live whenever one is underway.

What time does the Moon rise and set today?

Pick a location (or tap Use my location) and this page shows today's moonrise, moonset and the time and height of the Moon's highest point, in your device's time zone, computed in your browser. Because the Moon rises about 50 minutes later each day, some days have only a moonrise or only a moonset within the calendar day.

What was the moon phase on my birthday?

Jump the calendar on this page to any month from 1700 to 2200 and every day is drawn at its true phase, so you can read the Moon for any birthday, anniversary or historical date. The birthday tool further down finds the upcoming years your birthday lands on a full moon. One convention to know: dates are the modern (Gregorian) civil calendar throughout, so a date recorded before a country switched calendars (Britain and its colonies in September 1752) is Julian and sits about 11 days earlier than the same day here.

What are the traditional full moon names?

Each month's full moon has an old almanac name: the Wolf Moon in January, Snow in February, Worm in March, Pink in April, Flower in May, Strawberry in June, Buck in July, Sturgeon in August, Harvest or Corn in September, Hunter's in October, Beaver in November and the Cold Moon in December. The Harvest Moon properly belongs to the full moon nearest the September equinox, so about one year in three it falls in early October; this page names it that way.

What is a blue moon?

A blue moon is the second full moon in a single calendar month. Because the Moon's cycle is about 29.5 days, slightly shorter than most months, a month can occasionally hold two full moons; the second is called a blue moon. An older almanac definition counts the third full moon in a season that has four; the monthly definition used here is the one in common use. Either way, it is not actually blue.

What is a supermoon?

A supermoon is a full moon that falls near perigee, the Moon's closest point to Earth, so it looks a little larger and brighter than usual. There is no official cutoff, but a full moon closer than about 360,000 km is the common rule of thumb; such a moon looks roughly 7 percent wider and 15 percent brighter than an average full moon.

Why does the Moon turn red during a lunar eclipse (a blood moon)?

During a total lunar eclipse the only sunlight reaching the Moon has first passed through Earth's atmosphere, which scatters the blue light away and bends the red inward: the same physics that reddens every sunrise and sunset. So the fully shadowed Moon glows a dim copper red, popularly a blood moon, rather than going black. When an eclipse is underway or coming within two weeks, the Moon at the top of this page shows and announces it.

Why does the Moon look orange near the horizon?

A Moon seen low in the sky shines through far more air than one overhead, and air scatters blue light away first, leaving amber and orange. It is the same Moon at the same phase; an hour higher, the color washes back to gray-white. The effect is strongest at moonrise and moonset, which this page computes for your location, so a huge orange moon on the horizon is a matter of timing, not a special event.

Why does the Moon look upside down from the Southern Hemisphere?

There is no up in space: an observer in Australia stands oppositely oriented to one in Europe, so each sees the Moon rotated 180 degrees relative to the other. A waxing moon lit on the right from the Northern Hemisphere is lit on the left from the Southern. The moon on this page has a Southern Hemisphere toggle that rotates the view to match your sky.

What is the Metonic cycle?

The Metonic cycle is a span of 235 lunar months that comes out almost exactly equal to 19 years, the two differing by only about 2 hours. Because of this near-match, the Moon returns to nearly the same phase on the same calendar date every 19 years. It is named for Meton of Athens, who described it in 432 BC, and it still underlies the Hebrew calendar and the calculation of the date of Easter.

Does the moon phase repeat every 19 years?

Yes, very nearly. Because 235 lunar months almost exactly equal 19 calendar years, the Moon shows almost the same phase on a given date 19 years later, and again after 38, 57 and 76 years. The match drifts slowly: the months run about 2 hours longer than the years, and the Moon's uneven orbital speed and the calendar's leap days add a little more, so by four cycles (76 years, the Callippic cycle) the phase has slipped about a day and calendars drop a day to stay in step.

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