It really needs no introduction. Outside of the North Star, it’s the most famous navigational celestial object in history, even though it was only used once. It’s called the Star of Bethlehem or the Christmas Star even though it’s never been scientifically proven that it was indeed a star. Now, an astronomer says he has proof the Christmas Star was actually produced by a rare planetary alignment that may never happen again.

Grant Mathews, professor of theoretical astrophysics and cosmology in the Department of Physics in the University of Notre Dame’s College of Science, has been studying the origin of the Star of Bethlehem for a decade (nice work if you can get it). The uniqueness and brief observational record of the ‘star’ requires analyzing both biblical and historical writings as well ancient astronomical and astrological charts of the skies over Bethlehem and over ancient Babylon and Mesopotamia where the Zoroastrian priests referred to as the Magi are believed to have followed it from.

After ten years (and coincidentally just in time for his new book), Mathews believes he has the answer … and it isn’t ‘star’. Mathews announced this week that he’s found evidence that in 6 BCE, the sun, Jupiter, the moon and Saturn were all in Aries, the location at that time of the vernal or spring equinox. The location of the equinox is significant because it’s more often in another constellation. In fact, Mathews could not find another alignment of the sun, Jupiter, the moon and Saturn all in an Aries equinox for 500,000 years.

Was this planetary alignment so bright in the sky that these priests believed it to be a new star and followed it? This is where Mathews goes from astronomer to religious scholar and astrologist. He says having Jupiter and the moon in Aries at the same time signified the birth of a special ruler, while both Saturn and the vernal equinox symbolized new life and the beginning of spring. He speculates that the priests looked east, saw the alignment, did their astrological analysis and determined something happened that they should investigate.

I feel a kindred connection to these ancient Magi who earnestly scanned the heavens for insight into the truth about the nature and evolution of the universe, just as we do today.

That’s nice, but a little more astronomy would have been more informative. For example, David Weintraub, a professor of astronomy at Vanderbilt University, points out that the planetary alignment most likely began on April 17 of 6 BCE with the rising of Jupiter and lasted until December 19 of 6 BCE when Jupiter stopped moving west in the sky and changed directions to the east.

So it looks like something definitely happened in the sky over Bethlehem in 6 BCE. It’s also a good bet that there was a tree somewhere underneath it.