The Sun enters Ophiuchus today. A part of this large constellation lies between the traditional zodiac constellations Scorpius and Sagittarius. I’ve outlined its official border, set in 1930, in red. Stellarium
If you were born between November 29th and December 17th you’re being sold a zodiacal bill of goods. The astrology columns will tell you you’re a Sagittarius. Don’t believe it. You’re an Ophiuchian!
Ophiuchus (oh-fee-YOO-cuss) the Serpent Bearer represents a man with the snake Serpens coiled around his shoulders. To the ancient Greeks he was the god of medicine; the snake represented healing because of its seemingly magical ability to shed its skin as if being reborn.
Constellation boundaries before 1930 were often vague and varied from atlas to atlas. Now they’re precisely mapped with borders like those separating one country from another. Credit: Urania’s Mirror
Before 1930, the Sun passed seamlessly from Scorpius to Sagittarius during its yearly trip through the zodiac constellations. Now it spends 20 days in Ophiuchus between the two. In 1925, Eugene Delporte of the Royal Observatory of Brussels proposed the need for clear, universally-accepted constellation boundaries to the International Astronomical Union (IAU).
Boundaries were vague at the time and depended upon the star atlas you were using. Understandably, this created confusion for astronomers about what was where in the sky. If you discovered a new nova, you needed to let others know if it was in Sagittarius, Scorpius or wherever. Delporte drew up boundaries along existing vertical lines of right ascension (similar to longitude but applied to the sky) and horizontal lines of declination (latitude), extending the realm of Ophiuchus between Scorpius and Sagittarius.
Now the Sun can’t help but cross into Ophiuchus on November 29th. It doesn’t depart and enter Sagittarius until December 19th. A genuine zodiac constellation if I ever saw one, but will it ever get recognized as such? That’s up to Ophiuchians. Fight for your zodiacal rights!
Now let’s go a little further and examine the 12 traditional zodiacal signs.
The 12 traditional zodiac signs are the constellations the Sun appears to pass through during Earth’s yearly orbit around our star. Astrology allots an even one month per constellation. The actual time the Sun spends in each varies according to the size of the constellation.
Your astrological sign is determined by which of the 12 constellations the sun was in on the date of your birth 2,000 years ago. 2,000 years ago? Back when Rome was a world power, the Sun really did pass through Sagittarius from late November to late December. Not anymore. Because of something called precession, it occupies that constellation from December 17th to January 20th. All the other signs are likewise off about a month. So if you’re a Leo like I am, you’re really a Cancer in the 21st century.
Precession is the slow wobble of Earth’s axis over a period of 26,000 years caused by the combined gravitational tugging of the Sun and Moon. Spin a top and watch as it slow down. You’ll notice that the axis of the top describes a little circle (wobble) in the air before eventually tipping over. The Earth’s axis describes a similar circle in the sky. Since the pole star is determined by where our axis points, it follows that the pole star will shift position and change over that long cycle. Right now, Polaris in the Little Dipper sits in the hallowed spot at which our axis points, but in 14,000 A.D., brilliant Vega will occupy the position. Due to the cyclic nature of precession, Polaris will return as the North Star again in 28,000 A.D.
The slow, cyclic wobble of Earth’s axis called precession resembles the motion of a top slowing down. The wobble causes the pole star to change and the Sun to move westward along the zodiac. Credit: Earth and Planetary Magnetism Group ETH-Zurich
The Earth’s wobble also causes the sun to drift westward along the zodiac 1.4 degrees (about three sun diameters or an index finger held at arm’s length) per century. In 2,000 years, that adds up to 28 degrees or about one zodiac constellation width. Astrology practitioners stick with the Sun’s position two millennia ago, causing a disconnect between the Sun’s true position and one’s birth sign.
I’m no believer in astrology, but I think I understand why the practice hasn’t updated astrological signs to current times. Precession never stops. In another 500 years, the Sun’s position vs. the signs will have drifted even farther. It makes sense to adopt one time and stick with it. 2,000 years ago is as good as any.
If you’d like to know what your sign should be now in the 21st century, here’s an update:
Sagittarius: Dec. 17-Jan. 20. Capricornus: Jan. 20-Feb. 16. Aquarius: Feb. 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-Aug. 10. Leo: Aug. 10-Sept. 16. Virgo: Sept. 16-Oct. 30. Libra: Oct. 30-Nov. 23. Scorpius: Nov. 23-29. Ophiuchus: Nov. 29-Dec. 17