Yesterday, you were energetic and impulsive. Today, you may merely be dependable and loyal.

Horoscope readers who considered themselves sensitive Pisces found out they may actually be inventive Aquarians when an astronomer announced this week that the 12-sign zodiac chart, ranging from Capricorn to Sagittarius, is off-kilter.

The ancient Babylonians based zodiac signs on the constellation the sun was “in” — or aligned with — on a person’s day of birth. Since then, the moon’s gravitational pull has caused the Earth to “wobble” around its axis, ultimately forging a roughly one-month bump in the stars’ alignment.

As a result, “when (astrologers) say that the sun is in Pisces, it’s really not in Pisces,” Parke Kunkle, a board member of the Minnesota Planetarium Society, told the Minnesota Star-Tribune on Sunday. Kunkle, who called attention to the situation, teaches astronomy at Minneapolis Community and Technical College.

Based on where the stars are currently aligned, the revised chart makes room for a thirteenth sign — Ophiuchus (OFF-ee-YOO-kuss), which spans birthdays from Nov. 29 to Dec. 17.

In the evening sky, Ophiuchus consists of a vaguely house-shaped cluster of stars attached to a protruding line of other stars. This formation represents Asclepius, known in Greek mythology as the “serpent bearer” or the god of healing — the shedding of his snake skin symbolizes rebirth.

No one knows quite what this rogue new character has in mind for those born under its influence, who have been uprooted and shuffled without their consent.

In a former life — that is, three days ago — Sean Maguire, who turned 33 on Dec. 12, was a Sagittarius, a sign described as being stubborn. “Now that I’m not stubborn anymore,” said the reluctant Ophiuchus, “I’ve got to figure out what I really am.”

For astrologers who pride themselves on their ability to pry meaning from the stars, the new zodiac chart would seem to present devastating implications. How can a reading for, say, a Taurus hold true if the Taurus is now — or has been all along — an Aries?

But Rob Brezsny, an astrologer, says modern Western astrologers perfectly understand the Minnesota Planetarium Society’s point. It’s simply irrelevant to their work.

“The information upon which they base their hypotheses does not involve a study of distant stars or constellations,” he said in an e-mail. Rather, astrologers focus on the movements of the planets in the immediate solar system — and so, Brezsny says, the conventional 12-sign chart remains valid.

Jacqueline Bigar, who writes a syndicated horoscope column that appears in The Bulletin (see Page B5), says astrologers are “probably laughing their fanny off.”

And Arlene DeAngelus, an astrologer who has seen an estimated 5,000 clients, says she isn’t convinced by the 13-sign chart. “I would need to see some very good examples of them being accurate before I change mine,” she said.

Your ‘real’ horoscope

Astrology buffs should be using these dates, reflecting where the stars currently are aligned:

Capricorn Jan. 20-Feb. 16

Aquarius Feb. 16-March 11

Pisces March 11-April 18

Aries April 18-May 13

TaurusMay 13-June 21

Gemini June 21-July 20

Cancer July 20-Aug. 10

LeoAug. 10-Sept. 16

Virgo Sept. 16-Oct. 30

LibraOct. 30-Nov. 23

Scorpio Nov. 23-29

Ophiuchus Nov. 29-Dec. 17

SagittariusDec. 17-Jan. 20

— (Minneapolis) Star Tribune

Stars realigned

Ophiuchus celebrities include:

Britney Spears (Dec. 2)

Julianne Moore (Dec. 3)

Ozzy Osbourne (Dec. 3)

Jay-Z (Dec. 4)

Jeff Bridges (Dec. 4)

Taylor Swift (Dec. 13)

Manny Pacquiao (Dec. 17)