Zodiac sign dates, and why there is no cusp sign

Your zodiac sign is the sign the Sun stood in at the moment you were born. The Sun spends about 30 days in each of the twelve signs, beginning with Aries around March 20 or 21. The dates shift by a day from year to year, and if you were born on a changeover day, your birth time decides your sign: there is no cusp sign.

Zodiac sign dates for all twelve signs

When someone asks for your sign, they mean your Sun sign. The zodiac is a circle of 360 degrees, divided into twelve signs of 30 degrees each. Seen from Earth, the Sun moves through this circle once a year, about one degree per day.

These are typical dates in Universal Time, the reference time of astronomy. Depending on the year and on where you live, a change can fall a day earlier or later.

The last day of one sign is often the first day of the next. That is not a printing error: the Sun changes signs in the middle of a day, so the hours before the change belong to the old sign and the hours after it to the new one.

Why zodiac sign dates shift by a day

Two things move the dates around.

The change happens at a minute, not at midnight. The Sun crosses into the next sign at one precise moment, the same for the whole planet. The calendar date of that moment depends on where you are. A change at 2 a.m. Universal Time on April 20, for example, still falls on April 19 across the United States.

The calendar and the Sun do not match exactly. A normal calendar year has 365 days. The Sun needs a few hours longer than that for one full round of the zodiac. So every sign change comes a few hours later on the clock than the year before, until a leap day pulls it back. The moment wanders back and forth across midnight, and the date flips with it.

This is why one list ends Aries on April 19 and another on April 20. Both are right for some years. A fixed list is exact enough for every day except the one or two at each edge. For those, only a calculation for your year, place and time gives the answer.

Born on the cusp: there is no cusp sign

"Cusp" is the word for the boundary between two signs. People born within a few days of it often read that they are a blend of both.

Astronomically, there is nothing to blend. The boundary between two signs is a line without width. The Sun stands at 29 degrees of one sign, and a moment later at 0 degrees of the next. It is never in both.

Suppose the Sun moved from Aries into Taurus at 3 in the afternoon on the day you were born. A child born at 2 that afternoon is an Aries. A child born at 4 is a Taurus.

A few days away from the change, the question does not even come up. The Sun moves about one degree per day. Three days before the boundary it stands about three degrees inside its sign, as fully in that sign as on any other day.

A sign change is a minute on the clock, not a zone on the calendar. You were born on one side of it.

Why you can still feel like the neighboring sign

Many people born near a sign change do recognize themselves in both descriptions. That deserves a better explanation than a blended Sun: the Sun is only one of the bodies in your chart, and its closest companions never stray far from it.

• Mercury describes how you think and talk. Seen from Earth it is never more than about 28 degrees from the Sun, so your Mercury sign is your Sun sign or a neighboring sign.
• Venus describes how you love. It is never more than about 47 degrees from the Sun, so your Venus sign is your Sun sign or one of the two signs before or after it.
• The Moon describes what you need to feel safe. It changes signs about every two and a half days and can stand in any of the twelve.
• Your Rising sign, also called the Ascendant, describes how you meet the world. It changes about every two hours.

If you were born late in Aries, your Sun stands at the edge of Taurus. Mercury and Venus travel close to the Sun, so one or both often stand across the border. An Aries who thinks in the unhurried way of Mercury in Taurus and loves in the steady way of Venus in Taurus will find a lot of truth in the Taurus description, with a Sun that is entirely in Aries.

So the experience behind the cusp idea is real. Only the reason is different. You are not half one sign and half another: you are one Sun sign with planets next door. How Sun, Moon and Rising sign work together

What to do if you were born near a sign change

1. Check your birthday against the table. If it lies more than a day away from the dates at both ends of your sign, your Sun sign is settled.
2. If you were born on or right next to a changeover date, you need your birth time and place. Here are practical ways to find your birth time.
3. Have your chart calculated for your year, place and time. It shows the exact degree of your Sun.
4. Look at the signs of your Mercury, Venus and Moon. They often explain the pull toward the sign next door.

A Birth Chart Reading is calculated from your exact birth data and written for your chart, with the exact sign of your Sun and of every other planet.