Sun
Precession slightly alters the general positions of all we see in the heavens. (Creators.com illustration)

Anyone frequenting singles bars back in the 1970s or ’80s has surely heard the question: What’s your sign? And while most of us can recite the answer quickly, the truth is that few people know what it actually means.

It’s really quite simple.

The Earth orbits the sun once a year and causes the sun to travel in front of a thin band of star groupings that form what we call the zodiac. Now, if we could see the sun and stars together, we’d find that the sun appears against the stars of certain zodiacal constellations at different times of the year. Thus we know of such “sun signs” as Aries, Taurus and Sagittarius, each of which corresponds to a star grouping along the zodiac.

What most people don’t realize, however, is that since astrology’s origins several millennia ago, it has failed to keep up with our increasing knowledge of the cosmos. For example, modern scientists know that the Earth undergoes a 25,800-year wobble called precession. This slightly alters the general positions of all we see in the heavens and, more particularly, the positions of solar system bodies relative to the much more distant stars and the imaginary forms we call constellations.

So what, you ask?

Well, this means that the sign to which you think you belong is probably not the constellation against which the sun lay at the time of your birth — unless, of course, you were born thousands of years ago.

Suppose, for example, your birthday occurs on Nov. 16. You’ve lived your entire life believing your sign to be Scorpio. What a shock it must be to learn that, when you were born, the sun really lay in front of the stars of the constellation Libra.

Yikes!

And, if this isn’t disturbing enough, imagine celebrating your birthday on Nov. 29. On that day, the sun lies nowhere near Sagittarius; instead, it appears against the stars of a constellation that’s not even part of the zodiac: Ophiuchus, the serpent-bearer.

Now, lest you think that this is some kind of cosmic fluke, keep in mind that the sun actually spends three times as many days in front of the stars of Ophiuchus (from Nov. 29 through Dec. 17) as it does in front of Scorpius (Nov. 23-28), so one might think that Ophiuchus would be a sign in the horoscope tables. But where is it?

Perhaps it’s just a coincidence — or perhaps not — but my mother, younger daughter, nephew and several good friends were born under this sign. I still haven’t mustered the courage to tell any of them that they’re really Ophiuchans.

In fact, I can just hear the words of Lt. Uhura as she announces to starship Enterprise Capt. Kirk that some three-eyed, slimy-skinned aliens want to talk with him: “Captain, the Ophiuchans are on the hailing frequency.”

No, I think I’ll just keep my mouth shut and hope that the subject never comes up.

Click here to see the sun’s positions against the actual constellations throughout the year, compared with the astrological signs of those dates. And to learn more about the subject from another astronomer’s perspective, read Andrew Fraknoi’s article “An Astronomer Looks at Astrology.”

Dennis Mammana is an astronomy writer, author, lecturer and photographer working from under the clear dark skies of the Anza-Borrego Desert in the San Diego County backcountry. Contact him at mammana@skyscapes.com and follow him on Twitter: @dennismammana. The opinions expressed are his own.

Dennis Mammana

Dennis Mammana

Dennis Mammana is an astronomy writer, author, lecturer and photographer working from under the clear dark skies of the Anza-Borrego Desert in the San Diego County backcountry. Contact him at dennis@mammana.com and connect with him on Facebook: @dennismammana. The opinions expressed are his own.