THE tarot cards had long predicted that Matthew Foster was destined to fall in love with a Sagittarius. Then in 2009 he met Ben Mattson, a man he liked very much but who was a Capricorn.

“At first I thought, Oh, well, Ben is not the one I thought I was waiting for,” said Mr. Foster, 36, a playwright and theater director in Minneapolis. “But yet, we were still very compatible.”

For 15 years, he said, every tarot reader had produced the Knight of Wands, “meaning that the person I was supposed to hook up with was a Sagittarius.”

“It didn’t make too much sense,” Mr. Foster added.

Yet the fault, it seems, may not have been in him or Mr. Mattson but in the stars, or rather the alignment of the stars long used by astrologers. In December, Parke Kunkle, an astronomy professor at Minneapolis Community and Technical College, noted that the moon’s gravitational orbit had, over time, shifted the direction of Earth’s axis  meaning the North Pole was now aimed at a different part of the night sky, changing the signs of the zodiac.