Whether or not you believe in astrology, you probably know what your zodiac sign is and maybe even read your horoscope in the paper a couple times. So what if you learned that the sign you believed you were your whole life was wrong? If you've taken an introductory astronomy course, you've probably learned about the procession of the equinoxes. This is the phenomenon that the Earth wobbles on its axis over time. There is a 23 degree change in where the Earth falls in relation in relation to stars.

You probably don't know that there are several different zodiacs: the sign you were told you were since birth is in fact your "tropical" zodiac sign, the most common system used in the West. This is also known as the seasonal zodiac, because it follows the Earth's seasons. Aries marks the start of Spring, Cancer the start of summer, Libra the start of Fall, and Capricorn the start of winter (in the Northern hemisphere). But there is another zodiac called the Sidereal zodiac which is commonly used in the Eastern astrology, and it is not Earth-Centered or season-based. Instead, it uses the system of fixed stars. it is used extensively in India. The Eastern zodiac is older than the Western one. Basically, because of the Earth's wobbling (precession of the Equinoxes), the Western zodiac signs do not match up with the actual constellations anymore.

So if say you think you are a Pisces, for example, that doesn't mean that when you were born, the zodiac was actually in Pisces; there's a good chance it was in Aries. Head spinning yet? Or maybe you don't care. Anyway, in case you have even a little bit of curiosity about this, here are the actual dates:

Aries: April 18 - May 13
Taurus: May 13 - June 21
Gemini: June 21 - July 20
Cancer: July 20 - Aug. 10
Leo: Aug. 10 - Sept. 16
Virgo: Sept. 16 - Oct. 30
Libra: Oct. 30 - Nov. 23
Scorpio: Nov. 23 - Nov. 29
Ophiuchus: Nov. 29 - Dec. 17
Sagittarius: Dec. 17 - Jan. 20
Capricorn: Jan. 20 - Feb. 16
Aquarius: Feb. 16 - March 11
Pisces: March 11- April 18

In case you are not confused enough, there actually may also be a 13th sign. There is a theory that the 13th sign was ignored because in ancient times it was too difficult to divide 360 degrees by 13. Twelve was a lot easier. This 13th sign is called Ophiuchus, the Serpent-bearer, and its dates fall under the current sign of Sagittarius. It was said to have been "discovered" in 2011 by some astrologers in Minnesota but actually has been around for thousands of years. So hopefully, now you will never be able to use "so what's your sign?" as your next pick up line at a bar without second-guessing the person's answer. You're welcome.