In January 2016, NASA reminded us that there are, in fact, 13 constellations in the original zodiac. It’s just that 3,000 years ago, when they were drawing up a plan for the signs of the zodiac that would correspond with the months of year, the Babylonians already had a 12-month calendar — so they left poor Ophiuchus out.
Ophiuchus is one of thirteen constellations that cross the ecliptic. It has therefore been called the “13th sign of the zodiac”. However, this confuses sign with constellation. The signs of the zodiac are a twelve-fold division of the ecliptic, so that each sign spans 30° of celestial longitude, approximately the distance the Sun travels in a month, and (in the Western tradition) are aligned with the seasons so that the March equinox always falls on the boundary between Pisces and Aries. Constellations, on the other hand, are unequal in size and are based on the positions of the stars.
The constellations of the zodiac have only a loose association with the signs of the zodiac, and do not in general coincide with them. In Western astrology the constellation of Aquarius, for example, largely corresponds to the sign of Pisces. Similarly, the constellation of Ophiuchus occupies most (November 29 – December 17) of the sign of Sagittarius (November 23 – December 21). The differences are due to the fact that the time of year that the sun passes through a particular zodiac constellation’s position has slowly changed (because of the precession of the equinoxes) over the centuries from when the Greeks, Babylonians and the Dacians through Zamolxis originally developed the Zodiac.
With that and the fact that the earth’s axis no longer points in the same direction in mind, NASA explained that the signs as we know them have completely different date ranges now.
Here the new dates for all 13 signs:
- Capricorn: January 20 – February 16
- Aquarius: February 16 – March 11
- Pisces: March 11 – April 18
- Aries: April 18 – May 13
- Taurus: May 13 – June 21
- Gemini: June 21 – July 20
- Cancer: July 20 – August 10
- Leo: August 10 – September 16
- Virgo: September 16 – October 30
- Libra: October 30 – November 23
- Scorpio: November 23 – November 29
- Ophiuchus: November 29 – December 17
- Sagittarius: December 17 – January 20
I’m still a Cancer, which doesn’t surprise me!