Astronomers have long sought a cosmic explanation for the Bible’s Star of Bethlehem, the shining celestial object that, so the story goes, guided the wise men, or magi, from Jerusalem to greet the baby Jesus. One long-standing hypothesis held that the Star of Bethlehem was in fact a conjunction, perhaps between Jupiter and Saturn. But this holiday season, a scientist has presented a new contender: a comet.
Reports of a comet are found in Chinese records from 5 B.C.E., according to research published on December 3 in the Journal of the British Astronomical Association and written by Mark Matney, a planetary scientist at NASA, who conducted the research independently of the agency.
Matney recalls how, as a student, he worked at a planetarium that ran a Christmas sky show telling the story of the Star of Bethlehem, which rose in the southern sky until it appeared to come to a stop overhead. The planetarium show said that no known astronomical object could act in the way described by the story of the magi—Earth’s rotation means that everything in the sky rises in the east and sets in the west.
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“I remember sitting there saying, ‘Oh, I know one that could do that,’” Matney says. He suspected that a long-period comet from the mysterious Oort Cloud, which lies far beyond the planets of our solar system, could be the key.
If such a comet made an extremely close pass to Earth—about as close as the moon—it could create the strange appearance of a starlike object rising in the daylit sky and then appearing to stand still for a few hours. “A comet could stay in one place if it was basically on a ‘collision course’ with Earth,” Matney says. “That’s exactly what you would expect of an object that’s going to pass very, very close to the Earth.”
To test the idea, Matney turned to previous reports of Chinese records of a “broom star”—a term that has often been used to describe comets, in reference to their dynamic tail—that appeared in the spring of 5 B.C.E. The records have drawn the attention of Star of Bethlehem hunters for decades.
Intriguingly, the Chinese records seem to suggest that the strange star remained in the same constellation for 70 days—far too long for a comet, leading some astronomers to assume the object was perhaps a bright nova with a rayed appearance. Matney, meanwhile, says this description supports his collision-course-comet theory.
Other astronomers are less sanguine. Ralph Neuhäuser, an astrophysicist at Friedrich Schiller University Jena in Germany, who also studies astronomy through history, says that the Chinese record may be misleading. “The older the record, in general, the less information is left,” he says. Other astronomers have also suggested the search for an explanation for the star is misguided at best.
Matney does not deny the limitations of the records, stressing that he would prefer to have more sources. He says his goal is not to identify the Star of Bethlehem outright so much as to propose a valid astronomical object that could match its described behavior.
“I’m sure this paper will not be the final word on the Star of Bethlehem, but it seems to be a worthy contribution to forensic astronomy,” says Frederick Walter, an astronomer at Stony Brook University.
Additional reporting by Clara Moskowitz.