Your Moon sign

Why the Moon is the one that needs checking

The Sun moves about a degree a day, so a date nearly always settles its sign. The Moon is the fastest body against the stars: about thirteen degrees a day, half a degree an hour, a sign every two and a quarter days. On nearly one day in two it changes sign somewhere between midnight and midnight, and on that day the birth time decides which of the two signs it was. This page works that out for your own date and place rather than guessing, and when the day is not enough it says so and shows the hour the Moon moved on.

The phase

The phase is how much of the Moon was lit as seen from the Earth, which depends on how far round from the Sun it had travelled. It is the same everywhere on the planet at the same instant, and it changes slowly enough that the date is enough to know it. A waxing Moon is growing towards full and a waning one shrinking back towards new.

Using the calculator, step by step

Enter the date with the month chosen by name, the birth time as the clock showed it where you were born, and the town; tick the box if the time is unknown. The page works out the Moon at the birth minute, or at midday without one, and also at the local midnight before and after, to see whether the Moon changed sign that day. The first card gives the sign and degree, or two signs and the hour between them; the second gives the phase and how much of the Moon was lit; and once the sign is settled a third sets out how it is read, with a link to that sign’s own page.

Reading the day, with an example

The drawing runs from midnight to midnight across and the Moon’s degree up the side, with a dashed line at the edge of a sign. Take London on 1 January 1990. The Moon began the day at 26°33′ Aquarius and ended it at 10°01′ Pisces, crossing into Pisces at 06:10 in the morning. Without a birth time the page answers Aquarius or Pisces and gives that hour: born there before ten past six that day, the Moon was in Aquarius; born after it, in Pisces. A birth time known only to the nearest hour or two usually settles it. The hour is by the clock of the birthplace, not of wherever you are reading this.

Common confusions

A Moon sign from a Vedic calculator often differs from this one, because Indian astrology measures the zodiac from the stars, about 24° back from the tropical zodiac used here; its finer division of the Moon’s path is the nakshatra. The Moon sign is not the phase either: a full Moon can fall in any sign, always the one opposite the Sun, and the phase and sign for any day are on the Moon page and in the Moon calendar. The rising sign needs the birth time far more than the Moon does, since it changes every two hours or so, and what each sign is made of is under the signs.

How the Moon is read

In a chart the Sun is usually read as what someone is steering towards and the Moon as what they need to feel settled: habits, moods, the kind of comfort they reach for. The sign it is in is described in that sign’s own vocabulary, its element, its mode and its ruling planet. That is the language of the tradition, set out plainly here; it predicts nothing about anybody.