A billion years ago, on January 26th, I was in the early days of my career at the old Hansen Planetarium and I got a phone call from a woman with a question.
“My sign is Aquarius, but today’s my birthday and I just learned that the Sun is in Capricorn today. Why is the Sun in the wrong place for my sign?”
I was happy to explain.
“The signs of the zodiac and the calendar dates associated with them were created more than three thousand years ago. Since then the axis of Earth’s rotation has shifted quite a lot. Think of the way a spinning top slowly wobbles so that the top’s axis of rotation is moving in circle.
“Earth experiences this slow movement of its spin axis, too. This drifting of where the axis of rotation is pointing is called the Precession of the Equinoxes.
“A complete precession cycle takes about 26,000 years.
“From one January 26th to the next there’s not much of a change in where the Sun is along the zodiac, but in the last three thousand years the position of the Sun in the sky on any particular date has changed by more than one whole sign of the zodiac.”
My caller wasn’t happy about this. “This just makes a mess out of everything,” she said. “I’m going to have to check with my astrocartographer.”
“Astrocartographer?” I asked, bracing myself for the response.
“You know, deciding where you should live, based on your horoscope,” she explained.
Being young and tactless, I blurted out something like, “Are you serious?”
“Oh yes!” she said. “It works! I used to live in Aspen, but I was having a terrible time there. My astrocartographer said that I’d be happier in Park City, so I moved here and life is great!”
My underdeveloped capacity for impulse control got the better of me. “Does an astrocartographer ever recommend that someone move from Aspen to Des Moines?”
“I don’t think that’s funny at all,” she said – and hung up.
That was my first encounter as an astronomy educator with someone who took astrology seriously.
During my second encounter, an honest-to-gosh debate in front of an audience at a local library, I laid out all kinds of rock-solid evidence that astrology is so much mumbo-jumbo with no basis in reality.
The audience said I won the debate on the preponderance of evidence presented, but afterwards, as the astrologer and I walked out of the building to our cars, I noticed that the astrologer got into a spanking-new silver Mercedes.
I drove home in my rusting VW Beetle, thinking hard about who really “won” the debate that night.
It seems that someone is yet again pointing out what astronomers have known for centuries, that the precession of Earth’s poles makes determining horoscopes a bit of a mess, and that if we’re going to be honest with ourselves we need to slip a 13th zodiacal sign, Ophiuchus (“Oh-fee-yoo-kus”), in between Scorpius and Sagittarius.
I’ve known all along that on my birthday the Sun isn’t really in Sagittarius, as the newspaper horoscopes claim it is, but in Ophiuchus.
That’s right, I’m an Ophiuchan.
Now that the subject has made the news, and in the interest of promoting greater public awareness of the cosmos, I offer here the astronomically accurate zodiacal calendar. These are the constellations where the Sun actually is on the following dates:
Pisces: March 13 – April 18
Aries: April 19 – May 14
Taurus: May 15 – June 21
Gemini: June 22 – July 20
Cancer: July 21 – August 10
Leo: August 11 – September 16
Virgo: September 17 – October 31
Libra: November 1 – November 23
Scorpius: November 24 – November 30
Ophiuchus: December 1 – December 18
Sagittarius: December 19 – January 19
Capricorn: January 20 – February 16
Aquarius: February 17 – March 12
If you believe in astrology, then I’m unlikely to be able to use reason and scientific evidence to dislodge an idea that reason and scientific evidence played no part in creating. If you think the position of hunks of rock and clouds of hydrogen millions or billions of miles away should guide your real estate decisions, that’s your call.
If you don’t believe in astrology, then you probably already know that astrology fails every scientific test it’s ever been given, and I don’t need to rehash them here.
But if, for some reason, you want to know the many, many ways that astrology has been proven to have no connection to reality, you can start here, and I’ll leave it at that.
At least you now can know what your “true” birth sign is.