December 17, 2010. Copyright, 2010, Graphic News. All rights reserved

The enduring riddle of the Christmas star
By Julie Mullins

LONDON, December 17, Graphic News- At this time of year, what appears to be a particularly bright star is often visible in the night sky reminding many, no doubt, of the Star of Bethlehem. This is, in fact, the planet Venus, one of many astronomical objects cited in trying to understand this most enduring of enigmas.

Just about the only fact that can be stated with any degree of certainty is that Jesus was not born on December 25, 1AD. Christians did not celebrate his birth until at least 350AD and then, fairly arbitrarily, chose a mid-winter celebration the Romans called Saturnalia. In the 6th century, a monk called Dionysius Exiguus decided to standardise the calendar, counting back to Jesus’s birth. He missed out four years in the rule of Octavian, and so it is quite possible that Jesus was born sometime around 4BC.

The Wise Men were most likely Babylonian priests who derived much of their wisdom from astrology. They were particularly sensitive to heavenly portents, especially to what they called “wandering stars” and today we call planets. In 7BC, Jupiter and Saturn made three close passes of each other known, astronomically speaking, as a triple conjunction in the constellation of Pisces. Pisces was associated with the Jews, Saturn represented both justice and Palestine, while Jupiter was King of the gods, and thus the conjunction could have been interpreted as the coming of a Messiah.

The problem with this theory is that Matthew’s gospel refers specifically to a single star, and Jupiter and Saturn were not that close together. As others have pointed out, a much closer conjunction 59 years earlier should have alerted the Babylonians. With this in mind, American astronomer Roger Sinnott checked out the positions of other planets and found that the two brightest planets, Jupiter and Venus, approached so closely on June 17, 2BC, that they would have appeared to merge. The only problem is that Jesus was born during Herod’s rule and, by this time, Herod was almost certainly dead. 

Others have suggested comets, which appear as bright, elongated objects in the sky and give a sense of “pointing” towards the horizon. Medieval painter Giotto di Bondone’s Adoration of the Magi depicts a comet above the Wise Men, although artistic licence led him to “borrow” Halley’s Comet, which was visible in the year he painted the work. In reality, Halley’s Comet had appeared in 12BC, far too early for Christ's birth.  

The ancient Chinese, who were assiduous observers of the heavens, recorded a reasonably bright comet in the spring of 5BC. According to Professor Colin Humphreys of Cambridge University, this could fit the bill, and the triple conjunction two years earlier may have alerted the Magi to be on the alert for heavenly portents. But there are no records of this comet from the Middle East. In 1992, Ivor Bulmer-Thomas suggested that the star may have been Jupiter alone, which appeared to stand still in the sky on September 23, 5BC. His evidence came from recently deciphered cuneiform texts from Babylon which prove that astrologers could predict these events quite accurately.

A similarly intriguing possibility emerges from analysis of coins from Antioch dating from around this period. Michael Molnar, of Rutgers University, has found that they depict astronomical events that would not have been seen but could have been calculated. He believes that when Jupiter emerged from behind the crescent Moon just after sunset on the evening of April 17, 6BC, it might not have been visible because it was engulfed in twilight. But the Babylonians may have been aware of its presence and this could have prompted their journey.

Sources: Astronomy Now, Sky & Telescope, New Scientist, Royal Astronomical Society