How to Find the Zodiac Constellations Associated With Your Birthday

We often get questions from people asking us to identify the constellation that is associated with their birthdate, astrologically speaking. Over the course of the year, the Sun appears to trace out a circle across the stars that make up the zodiac constellations. At some point over the year, the Sun will appear ‘behind’ one of these constellations and that particular constellation is known as your star sign.

The constellations that mark the Sun’s apparent path through the year are called the Zodiac constellations, and they include 7 ancient figures representing animals (Aries — ram), Gemini — twins, Cancer — crab, Leo — lion, Libra — scales, Scorpio — scorpion, Sagittarius — archer and Capricornus — goat, plus Pisces — fish. The 13 constellations of the zodiac, including the extra one not listed in astrological horoscopes, occupy a narrow band 8-9 degrees wide on either side of the Sun’s orbit, the ecliptic.

Astronomy constellations are imaginary groupings of stars whose names were arbitrarily chosen by ancient observers, usually for the shapes they suggest or the mythological creatures or events they resemble. These groups of stars make a two-dimensional map of the sky that is very useful for orientation. This made life easier for early astronomers, who could simply look at the map to figure out where they were in the sky and what they might be able to see, and for travelers and sailors, who used them for navigation.

Because the constellations of the zodiac are recognizable and easy to find, they have become the basis for modern astrology. The problem is that these constellations don’t look anything like the animals they were meant to represent and, therefore, most modern horoscopes are way off.

Fortunately, astronomy can help you determine which constellation the Sun was behind on your birthday by using the current positions of the zodiac constellations and their background stars, as illustrated below. These coordinates are accurate to within 1 degree.

If you know which constellation is associated with your star sign, you can easily find it at nighttime by tracing a line from the bright star in that constellation to another star near its border. For example, to find Aries, start with Mirach (Beta Aries), the first of three bright stars in Pegasus’ Square asterism, and continue tracing outward from it to the other nearby stars. You will soon reach a curved, oval-shaped constellation that includes the bright stars of Aries, forming its head. Similarly, to find Pisces, start with the bright star Alpheratz (Beta Aquarii), the bottom right star in the Square of Pegasus, and continue outward from it until you hit the rounded constellation of Pisces, the fish.

You can also use this technique to find the other constellations that mark the Zodiac. Currently, the bright star Venus is in Taurus, Mars is in Scorpius and Jupiter is in Sagittarius. In the western pre-dawn sky, you can easily spot these constellations from their distinctive shapes.