Your moon sign is the sign of the zodiac the Moon was passing through when you were born. The Moon moves on to the next sign every two to three days, so your birth date usually settles it. Your birth time only decides it on a day when the Moon changed sign.
How do you find your moon sign?
- Write down your birth date, and your birth time if you know it.
- Note the time zone of your birth time, including whether summer time applied.
- Look up the Moon's sign for that date in a birth chart calculator or an ephemeris, a table of the sky's positions day by day.
- Check whether the Moon changed sign during your birth date.
- If it did, compare your birth time with the moment of the change.
Always needed: your birth date. On a change day you also need your birth time and time zone, because the Moon was in one sign before the change and in the next sign after it.
When does your birth time matter?
Only on a change day. If the change time you find is given in UTC, turn it into the local time where you were born before you compare.
- h17
- m31
- EST-5
The Moon enters Virgo at 17:31 UTC. New York is on EST, UTC-5, in January: 17:31 - 5 h = 12:31 local time.
Born before about 12:31 that day, the moon sign is Leo; born from about 12:31, it is Virgo.
If your recorded time is close to the change, a few minutes of error can still leave the answer open.
Why can the time zone change the answer?
A sign change happens at one moment for the whole Earth, but clocks in different places show different dates for it.
| Clock | Time zone | Local date and time |
|---|---|---|
| UTC | UTC | 18 Jan, 05:44 |
| New York | EST, UTC-5 | 18 Jan, 00:44 |
| Los Angeles | PST, UTC-8 | 17 Jan, 21:44 |
The change times in this article were calculated with Astronomy Engine, an open-source library (version 2.1.19), and rounded to the minute.
So 17 January 1998 is a change day for a birth in Los Angeles, but not for a birth in New York. In Los Angeles that evening, a birth at 21:00 has a Virgo Moon and a birth at 22:00 has a Libra Moon.
If you don't know your birth time, you still know your moon sign when the Moon stayed in one sign for your whole local birth date. If it changed sign that day, you have two possible moon signs, and only the time can decide between them.
What this means for your day
For your day
Do
Check whether the Moon changed sign on your birth date before you trust one sign.
Don't
Don't forget summer time when you turn a birth time into UTC.
Questions people ask
Does my moon sign ever change?
No. It is fixed by the moment you were born. The Moon you see tonight is in its own sign, which astrologers compare with your birth chart as a transit.
Why does a Vedic chart give me a different moon sign?
Vedic astrology uses the sidereal zodiac, measured against the stars, while most Western astrology uses the tropical zodiac. The examples here use the tropical zodiac. In one sidereal system the signs were around 23 degrees behind the tropical signs in 2020, so the Moon can fall in the sign before.
Sources
- Wikipedia: Horoscope. A birth chart shows the positions of the Sun, Moon and planets at the moment of birth.
- Wikipedia: Orbit of the Moon. The Moon completes one orbit against the stars in about 27.32 days.
- Wikipedia: Ephemeris. Tables of sky positions, also used by astrologers.
- Wikipedia: Eastern Time Zone and Wikipedia: Pacific Time Zone. EST is UTC-5 and PST is UTC-8.
- Wikipedia: Astrological transit. Transits interpret the planets' ongoing movement against the birth chart.
- Wikipedia: Sidereal and tropical astrology. The two zodiacs and the gap of around 23 degrees in 2020.
- Astronomy Engine, version 2.1.19. The Moon's sign-change times on 15 and 18 January 1998, in UTC, tropical zodiac.