The fastest body in your chart
The Moon circles the whole zodiac in about 27.3 days. That means it stays in each sign for only two to two and a half days before moving on, far quicker than the Sun or any planet.
This speed is why two people born a few days apart can share a sun sign but have completely different Moon signs. It is also why a birthday alone is not always enough to settle the answer.
When your birth time decides the sign
On most days the Moon stays in one sign from midnight to midnight, and the date is all we need. On roughly two or three days of every week, though, it crosses from one sign into the next at some hour.
If you were born on one of those days, the hour decides which of two neighboring signs is yours. Without a time we use noon, which can land on the wrong side of the change, so a birth certificate time is worth looking up.
What the Moon is linked with in astrology
Astrologers associate the Moon with emotions, instinct and the need for comfort. If the Sun is read as the self you aim to become, the Moon is the self you already are when nobody is watching.
Your Moon sign is often used to describe what helps you feel safe, how you react under stress and the kind of care you give and want to receive. It is also linked with memory, habits and early home life.
Moon signs by element
A fire Moon is commonly read as needing excitement and quick expression of feelings. An earth Moon tends to be linked with comfort through routine, food and physical security.
Air Moons are described as processing emotions by talking or thinking them through, while water Moons are associated with deep, private feelings and strong intuition. You can compare these on the water signs and earth signs pages.
How we find the Moon's position
The Moon's path is the most complex of all the bodies we track, because Earth's and the Sun's gravity both pull on it. Astronomy Engine models those effects and gives the Moon's longitude to within about one arcminute.
We convert your local birth time to UTC with the time zone history of your birthplace before computing. To see where the Moon is right now, check today's moon sign, or place your natal Moon among your other placements with the Big Three calculator.