The question comes up each Christmas, sent by email or scrawled on paper and shoved into the Vatican Observatory’s in-box: What was the Star of Bethlehem?
“I can see why people would want to ask Vatican astronomers,” writes Father Paul Mueller in the new book Would You Baptize an Extraterrestrial? (by Guy Consolmagno, SJ and Paul Mueller, SJ, Image, 2014). “After all, the Star has connections with both faith and science. Since it appears in the Bible, people of faith want to know about it: Was there really a Star? Was it a miracle, or can it be explained by science? What does the Star mean—what does it signify? And since the Star would have been an observable phenomenon, scientists are interested in figuring out whether there really was a Star and what sort of thing it might have been.”
Both authors are members of the research staff at the Vatican Observatory; Consolmagno specializes in planetary physics, geology, and the study of asteroids and meteorites. Mueller’s expertise is the history and philosophy of science, particularly physics and astronomy.
The authors note that it’s doubtful the Star of Bethlehem was a known constellation, as people would have been familiar with its appearance each season. A nova is also unlikely, as they appear fairly often, say the authors—every ten years or so. What about a supernova? (The last naked-eye supernova in our galaxy was observed in 1604.) Probably not, says Consolmagno. While supernovas could be seen in the daytime—and would therefore be dramatic—they leave behind remnants. “But there are no independent reports of a supernova around the time Jesus was born,” he writes. “And there are no unaccounted-for supernova remains from two thousand years ago. So it seems to me that astronomy can pretty much rule out the idea that the Star of Bethlehem was a supernova.”
Perhaps a comet? Dubious, thinks Consolmagno. In ancient times, comets were universally interpreted as signs of doom. “Nowadays most attempts at giving a possible scientific explanation for the Star of Bethlehem involve looking for interesting or unusual conjunctions of the planets.” The authors consider astronomer John Mosely’s idea that the conjunction of Jupiter and Venus in August of 3 BC would have interested astrologers. The encounter of Jupiter and Venus on June 17, 2 BC—so close as to appear to be one bright star—might have led to the sighting.
“It’s not as though modern astronomy has shown that the story in Matthew about the Star of Bethlehem cannot be true,” writes Mueller. “Just the opposite: modern astronomy makes it possible to come up with a surfeit of possible explanations for the Star.” (The authors note that more than 400 books have been written on the topic.) But even if no extremely unusual astronomical events happened 2,000 years ago, says Mueller, that wouldn’t make the Biblical accounts false. “It’s a mistake to try to read every line of Scripture as if it were intended by its author to be understood as a literal account of historical events that actually happened,” he writes. “That’s just not how many parts of Scripture were meant to be read.”