Ophiuchus, the 13th Zodiac sign

While most people probably make their important life decisions based on, oh I don’t know, common sense and things like that, there are a whole lot of people around the world who do take their star signs and horoscopes seriously, and with more than 25 percent of respondents in a recent survey calling astrology “very scientific”, there’s a big problem here.

NASA did some new calculations and determined there are actually 13 zodiac signs instead of 12, meaning that 86 percent of all people were actually born under a different sign! The 13th zodiac sign is Ophiuchus. It’s pronounced “oh-FEW-kuss.” Ophiuchus has been used in sidereal and Vedic astrology, but is not commonly practiced in the western astrology.

Have you heard that we changed the zodiac signs? Nope, we didn’t…we just did the math. Info: https://t.co/TsBgxmojZZ pic.twitter.com/sf62deofox

— NASA (@NASA) September 22, 2016

NASA clarifies on their blog that they study astronomy, not astrology. They didn’t change any zodiac signs, they just did the math. Astronomy is the scientific study of everything in outer space. Astronomers and other scientists know that stars many light years away have no effect on the ordinary activities of humans on Earth.

The Babylonians lived over 3,000 years ago. They divided the zodiac into 12 equal parts – like cutting a pizza into 12 equal slices. They picked 12 constellations in the zodiac, one for each of the 12 “slices.” So, as Earth orbits the sun, the sun would appear to pass through each of the 12 parts of the zodiac. Since the Babylonians already had a 12-month calendar (based on the phases of the moon), each month got a slice of the zodiac all to itself.

But even according to the Babylonians’ own ancient stories, there were 13 constellations in the zodiac. So they picked one, Ophiuchus, to leave out. Even then, some of the chosen 12 didn’t fit neatly into their assigned slice of the pie and crossed over into the next one.

When the Babylonians first invented the 12 signs of zodiac, a birthday between about July 23 and August 22 meant being born under the constellation Leo. Now, 3,000 years later, the sky has shifted because Earth’s axis (North Pole) doesn’t point in quite the same direction.

The constellations are different sizes and shapes, so the sun spends different lengths of time lined up with each one. The line from Earth through the sun points to Virgo for 45 days, but it points to Scorpius for only 7 days. To make a tidy match with their 12-month calendar, the Babylonians ignored the fact that the sun actually moves through 13 constellations, not 12. Then they assigned each of those 12 constellations equal amounts of time.

While this explanation should clear up any remaining confusion, NASA stresses one major point: Astrology is something else. It’s not science.

Zodiacal signs are of equal length whereas the zodiacal constellations are not equal in length. Whether or not you believe horoscopes are worthwhile, it seems Ophiuchus won’t be disrupting our astrological zodiac any time soon.

Filed under: Nature & Environment, Science & Technology Tagged: Astronomy, Constellation, Mesopotamia