Sofia Whitcombe began her day with the startling realization that she might not be exactly who she thought she was.

“My whole life, I thought I was a Capricorn,” the 25-year-old publicist said. “Now I’m a Sagittarius? I don’t feel like a Sagittarius!”

“Will my personality change?” she mused. “Capricorns are diligent and regimented, and super-hardworking like me. Sagittarians are more laid back. This is all a little off-putting.”

Countless people reacted on social networks Friday to the “news” that the stars have shifted alignment, astrologically speaking.

No matter that the man who started it all said it was an old story — 2,000 years old, actually — and that astrologists were insisting it wouldn’t change a thing.

In an interview Sunday in the Star Tribune of Minneapolis, astronomy instructor Parke Kunkle explained that the Earth’s wobbly orbit means it’s no longer aligned to the stars in the same way as when the signs of the zodiac were first conceived, about 5,000 years ago. That means, he said, that when astrologers say the sun is in Pisces, it’s really in Aquarius, and so on.

“Astronomers have known about this since about 130 B.C.,” Kunkle said Friday in his office at Minneapolis Community and Technical College. “This is not new news. Almost every astronomy class talks about it.”

One of the more fascinating elements of the story was talk of a new sign altogether.

By the reckoning of Kunkle and other astronomers, astrologers are not only a month off in their zodiac signs, but they are neglecting a 13th constellation, Ophiuchus the Serpent Bearer, for those born from Nov. 30 to Dec. 17.