Zodiac sign by birth date: your baby's sign and constellation
Your baby's zodiac sign follows from the birth date: Aries runs from 21 March to 19 April, and the table below gives all twelve signs. The constellation the Sun stood in that day is a separate answer. For most of the year it is the constellation one place earlier, and from late November to mid-December it is Ophiuchus, which has no sign.
Which zodiac sign goes with which birth date?
A zodiac sign is one of twelve equal slices of the Sun's yearly path across the sky, each 30 degrees wide, counted from the point where the Sun stands at the March equinox. Wikipedia's zodiac article lists these dates for the Sun's entry into each sign:
| Sign | Birth dates |
|---|---|
| Aries | 21 March to 19 April |
| Taurus | 20 April to 20 May |
| Gemini | 21 May to 20 June |
| Cancer | 21 June to 22 July |
| Leo | 23 July to 22 August |
| Virgo | 23 August to 22 September |
| Libra | 23 September to 22 October |
| Scorpio | 23 October to 21 November |
| Sagittarius | 22 November to 21 December |
| Capricorn | 22 December to 19 January |
| Aquarius | 20 January to 18 February |
| Pisces | 19 February to 20 March |
Lists in print can differ by a day at the edges. The newspaper table that astronomer Jeremy Tatum quoted in 2010 starts Taurus on 21 April and Gemini on 22 May.
Why does a birth near a sign boundary need the exact year and time?
Each sign starts at a precise moment, and that moment drifts by hours from one year to the next. Aries begins at the March equinox, which the US Naval Observatory puts at 09:01 Universal Time on 20 March 2025, at 14:46 on 20 March 2026 and at 20:25 on 20 March 2027.
So a baby born on 20 March 2026 before 14:46 Universal Time arrived with the Sun still in the sign of Pisces, and a baby born later that day with the Sun in the sign of Aries, even though the table above calls the whole of 20 March Pisces. The other boundaries move in the same way, because the Gregorian calendar drifts slightly against the Sun's year.
In the table above, every boundary falls between the 18th and the 23rd of a month. If your baby was born on one of those days, look up the moment the Sun entered the next sign in that year, convert it to your own time zone and compare it with the time of birth. For Aries, the Naval Observatory's tool gives that moment for any year from 1700 to 2100; for the other signs you need an ephemeris, a table of the Sun's position, for that year.
Which constellation was the Sun really in?
A constellation is an area of sky with an official border. The International Astronomical Union agreed on 88 of them in 1922, and Eugène Delporte of the Royal Observatory in Brussels drew their borders along lines of right ascension and declination; the IAU approved them in 1928 and published them in 1930. Measured against those borders, the Sun's path crosses thirteen constellations, Ophiuchus among them.
The signs and the constellations have drifted apart because Earth's axis slowly wobbles, one full circle in about 26,000 years. In ancient times the March equinox point lay in the constellation Aries; NASA's Goddard explainer says it moved into Pisces around the year 1 and is now passing into Aquarius. Tatum's conclusion, in the Journal of the Royal Astronomical Society of Canada, is that for most of the year the Sun stands in the constellation adjacent to the sign's namesake, about a month out of step. Born in late May, he is a Gemini by sign, and the Sun was in Taurus.
These are the dates in Tatum's table. He notes they can move by a day, at most two, with the year and your time zone.
| Constellation | The Sun is in it |
|---|---|
| Aries | 20 April to 14 May |
| Taurus | 15 May to 22 June |
| Gemini | 23 June to 21 July |
| Cancer | 22 July to 11 August |
| Leo | 12 August to 17 September |
| Virgo | 18 September to 1 November |
| Libra | 2 November to 24 November |
| Scorpius | 25 November to 30 November |
| Ophiuchus | 1 December to 18 December |
| Sagittarius | 19 December to 20 January |
| Capricornus | 21 January to 16 February |
| Aquarius | 17 February to 12 March |
| Pisces | 13 March to 19 April |
Laid side by side, the two tables in this post give the same name on only 36 days of the year. On 295 days the Sun stands in the constellation one place before the sign: a baby born on 1 May is a Taurus, with the Sun in Aries.
On most days of the year, the Sun on the birth date stands in the constellation one place before your baby's sign.
Why is Ophiuchus called the 13th constellation?
The Sun spends 18 days inside the borders of Ophiuchus, the Serpent Bearer, every year from late November to mid-December, according to Royal Museums Greenwich, home of the Royal Observatory. That is longer than its stay in Scorpius, which Tatum puts at six days. The ancient Babylonians and Greeks, working with a twelve-month calendar, chose twelve constellations and left Ophiuchus out of the pattern.
Tatum also corrects an explanation he has heard even from astronomers. Precession moved the equinox point from Aries into Pisces, but it has nothing to do with Ophiuchus: the Sun's path crosses it because of the way the IAU drew the borders in 1930.
What does each constellation look like, and when can you see it?
The IAU defines a constellation by its area and leaves stick figures informal, so the same constellation is drawn in several ways and the number of stars in "the" figure depends on the chart. This table gives each constellation's brightest star and how many stars our Sterre design joins into its figure.
| Constellation | Brightest star | Stars in our Sterre figure |
|---|---|---|
| Aries | Hamal | 5 |
| Taurus | Aldebaran | 7 |
| Gemini | Pollux | 8 |
| Cancer | Tarf | 5 |
| Leo | Regulus | 9 |
| Virgo | Spica | 8 |
| Libra | Zubeneschamali | 5 |
| Scorpius | Antares | 12 |
| Ophiuchus | Rasalhague | not drawn |
| Sagittarius | Kaus Australis | 8 |
| Capricornus | Deneb Algedi | 8 |
| Aquarius | Sadalsuud | 9 |
| Pisces | Alpherg | 11 |
The alpha star is sometimes outshone. In Gemini, Pollux, beta Geminorum, is the brighter twin: the IAU's star catalogue gives it magnitude 1.16, against 1.98 for Castor, alpha Geminorum.
On the birth date itself you cannot see the constellation the Sun is in. The California Academy of Sciences puts it plainly: your constellation is in the background when you look towards the Sun on your birthday. It returns to the night sky months later. NASA's example is 21 September, when from the northern hemisphere you can probably see Pisces, the constellation the Sun crosses in March and April. Royal Museums Greenwich calls July a good month for Ophiuchus, whose stretch of the Sun's path falls in December.
How can you keep your baby's birth sky?
Our Sterre style draws a constellation inside a thin ring, with the name of the sign beneath it. Sterre follows the sign. It picks one of the twelve signs from the birth date with the first table in this post and draws the constellation that shares the sign's name. It does not use the time of birth, and it never draws Ophiuchus. Until you enter a date it shows a small cluster of stars.
Sterre sits in the Moon & stars group of our designs, next to Luna, which prints the moon phase on the birth date. If you would rather mark the month with a flower, our guide to birth flowers by month lists them. Sterre comes as a framed poster, on canvas or as a pack of birth cards.
To see your baby's sign drawn, open Sterre in the poster editor and type the birth date, or start a pack of birth cards with it.
Questions parents ask
What if my baby was born on a cusp?
A cusp baby, born on the day one sign hands over to the next, still has one sign. Which one depends on whether the birth came before or after the moment the Sun crossed the boundary that year, so check that moment against the time of birth. Sterre goes by the date alone and uses the dates in the first table.
Is my baby an Ophiuchus?
If your baby was born from about 1 to 18 December, the Sun was in the constellation Ophiuchus, by Tatum's dates. The sign is still Sagittarius up to 21 December, because the twelve signs leave Ophiuchus out.
Does the time of birth change the zodiac sign?
Only on a day when the Sun crosses into the next sign, which happens about once a month. On 20 March 2026, a birth before 14:46 Universal Time was Pisces and a birth after it Aries.