Astronua

Moon phase calculator

Calculate the Moon's phase, illumination, age and sign for the date, time and place you choose, plus the next Full Moon and New Moon and a phase calendar for the month.

If you don't know the time, leave 12:00; the Moon sign and rising sign depend on it.

We find the location from the district, province and country, then add the latitude, longitude and the time zone in force on that date (including daylight saving time).

Enter coordinates manually

If the place can't be found, enter the latitude, longitude and the UTC offset at the time of birth. When these are filled in, they are used instead of the place names.

Your birth date, time, place and name are stored only in this browser and are never sent to our server.

How is the Moon phase calculated?

  1. Elongation

    The difference in ecliptic longitude between the Moon and the Sun (0–360°) is calculated. 0° is the New Moon, 90° the first quarter, 180° the Full Moon, 270° the last quarter.

  2. Eight phases

    The angle is divided into 45° slices to find one of eight phases: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, Waning Crescent.

  3. Illumination

    The lit fraction of the Moon's disc is calculated with astronomy-engine's illumination function.

  4. Next Full Moon and New Moon

    The moments the Moon reaches 180° and 0° from the Sun are searched to the minute and shown in your chosen place's time.

Moon age = (Moon longitude − Sun longitude) / 360° × 29.53 days

Why do Moon phases matter?

The waxing Moon is seen as suited to beginnings, plans and growth; the waning Moon to completion, cleansing and letting go. The New Moon is a time for setting intentions, the Full Moon a time to see results.

Frequently asked questions

Why is the place needed?

The phase happens at the same moment everywhere, but the local date and time depend on the place; we use it to show when the Full Moon happens in your time.

Which sign is the Moon in?

The Moon stays in each sign for about two and a half days; the calendar also shows the Moon's sign each evening.

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