Born Under a Full Moon: How to Check Yours

How to work out your own birth phase

This is arithmetic rather than interpretation, and you can do it with any chart that gives degrees. The lunar month is the Moon pulling ahead of the Sun by 360 degrees over 29.53 days. Where it had got to when you were born is your phase.

1. Find your Moon's position in zodiac degrees. Each sign is 30 degrees, counting from 0 at the start of Aries, so 12 degrees of Gemini is 60 plus 12, which is 72.
2. Do the same for your Sun.
3. Subtract the Sun from the Moon. If the answer is below zero, add 360.
4. Look the number up in the table. That is your phase.

Each phase covers 45 degrees, which the Moon crosses in about three and three quarter days. So roughly one person in eight shares your birth phase, and the whole cycle repeats every 29.53 days. That is a far wider net than a birth chart and a much narrower one than a Sun sign.

What a Full Moon birth is read as

Born at an opposition, and relationships are where the chart gets worked out. Awareness tends to arrive through another person reflecting something back.

It sits between the Waxing Gibbous Moon, which is about refining, adjusting, asking what it is for, and the Waning Gibbous Moon, which is about passing it on. If you were born within a few hours of a boundary, read both. The phases are a continuum that somebody drew eight lines across, not eight boxes.

The same cycle, running slowly, across your life

There is a second version of this that almost nobody mentions on a page about birth phases, and it is the more useful one. In secondary progressions, where one day after birth stands for one year of life, the Moon pulls ahead of the Sun at about twelve degrees a year instead of twelve degrees a day. So the whole lunation cycle plays out once over roughly twenty-nine and a half years of living.

That gives a progressed new moon at about 29 and again at about 59, a progressed full moon at about 15 and 44, and the eight phases spread across the gaps at roughly three and a half years each. People who track it describe the progressed new moon as the clean start and the progressed full moon as the point where whatever started then becomes visible, for better or worse.

It is worth checking against your own history, because unlike the birth phase it moves, and you can therefore test it. What else lands around 29 is covered here, and what lands at 44 here.

Where the eight-phase reading comes from

The division into eight is modern. It was set out by Dane Rudhyar in the 1960s, drawing on an older idea of the lunation cycle, and it is the version in general use today. The phases themselves are as old as looking up. The personality reading attached to them is about sixty years old, which is worth knowing before deciding how much weight to give it.

What this is not

It is not your Moon sign, and the two get mixed up constantly. Your Moon sign is which sign the Moon was in. Your birth phase is how far ahead of the Sun it was. You can have the Moon in Leo at any phase at all, and the two say different things.

It is also not the same as which phase is in the sky tonight. That is a shared calendar. Your birth phase is fixed for life and does not change.

If you want it calculated rather than worked out by hand

The arithmetic above needs your Moon's degree, and the Moon moves about half a degree an hour, so a chart built without a birth time can put it in the wrong sign entirely. Here is how to find your birth time.