On Jan. 13, 2011, just two weeks before Saturn turned retrograde in Libra, humans in the Western world

woke to the disruptive report that their star sign had changed. Or rather that their star sign was probably

never the one they thought it was. The response was astronomical, even though many Americans think about the zodiac only when

reaching for conversation with models and hunky yoga teachers. Apparently, the best way to get folks to

care about their star sign was to try to change it. "Despite not really believing in astrology, I hereby insist

on remaining an Aries," said TV host Rachel Maddow, echoing the prevailing sentiment.

All the hubbub was set off inadvertently by Parke Kunkle of the Minnesota Planetarium Society. He

observed to the local paper that because of the idiosyncrasies of the earth's orbit around the sun, the

stars do not match up with their allotted zodiac months. For example, the sun no longer appears in the

constellation, or house, of Aries in March and early April, and it hasn't for hundreds of years. (It now

makes its annual flyby in mid-April and early May.) Moreover, there's an additional constellation that the

sun passes through in December known as Ophiuchus, which never made it into the zodiac we thought

we knew. The common conclusions: people who believed they were one star sign were probably the one

prior, hardly anyone was a Scorpio, and there was a new group, signified by a guy holding a snake,

whose members had no idea how they were supposed to behave.

Astrologers were infuriated by all the fuss. "This whole brouhaha is about the ignorance of astronomers,"

says astrologer and author Rick Levine. "Astrologers have actually known about this for some 2,000

years."

Western astrology, as it happens, is not predicated on the movement of the sun in relation to the

constellations. It's based on the movement of the sun and planets through the seasons. Back in the 2nd

century, when astrology was codified by Ptolemy, the sun was probably in Aries on the first day of spring.

That's the vernal equinox, when the sun is directly over the equator, making the earth dark and light for

about the same length of time. The tropical zodiac, as it's known, still takes that date, March 21, as the

start of Aries and divides the year and the 360-degree path traced by the sun around the earth into 12

parts. From that chart, astrologers make all their predictions. "The stars are irrelevant to the zodiac," says

Tarot.com astrologer Jeff Jawer.

So the good news is that the star sign you were born under is still your sign. The bad news is that it's not

technically a star sign. And it's an open question, given that astro- is from the Greek for star, whether

astrology didn't help bring on this confusion. "We could call it planetology," acknowledges Levine. "But

that would be stupid."

Indeed. But since only about 25% of Americans believe in astrology, why the big reaction? It's akin to

teetotalers' caring whether a bar stocks Gordon's or Beefeater. What role does the zodiac really play in

our worldview?

Tellingly, the news took off mostly on Twitter and Facebook, the social networks where people go to craft

the narrative of their lives. This was a perfect status update. For those who clung to their sign, it was a

chance to reaffirm who they believe they are. For those who embraced a new one, it was an occasion to

edit their story — or at least write something funny.

Now that it transpires the zodiac is based on the seasons, not the stars, we can all return to our original

sign. Unless, of course, you were born in the southern hemisphere, where the vernal equinox is in

September. Psst, Libra, you may really be an Aries.