Christmas or not Christmas?

“Where is He who has been born King of the Jews, who has just been born? For we saw His star when it rose…” The Gospel according to Matthew is the only one to mention the presence of a bright star that guided the Three Magi to the stable where Jesus was born. This statement is the starting point for our inquiry: was there an extraordinary astronomical phenomenon around year 1 that could be identified with the biblical text?

The Bible itself already provides a few clues. Firstly, we can read that Jesus was born during the reign of King Herod. Yet, the latter died shortly after a lunar eclipse which happened in the year 4 B.C. Secondly, the census commanded by Cesar, and which was the reason Marie and Joseph fled toward Bethlehem, took place in the year 8 B.C. Thus Jesus’ birth is calculated as being between years 8 B.C. and 4 B.C.

Did something extraordinary happen in the sky during those four years?

A supernova, a violent explosion of a star at the end of its life, could provide a good explanation. Unfortunately, these explosions are very rare in our galaxy, and do not remain visible for very long – just two to three weeks. And yet the legend states that the Magi set off after they had observed a luminous phenomenon. They observed the same phenomenon a few weeks later in the sky over Jerusalem, which guided them toward Bethlehem. The unique characteristic of a supernova gives little credence to this hypothesis – it’s estimated that there are only three per century in our galaxy.

Comets have the advantage of coming back in a recurrent manner, since they orbit around the sun. It is a spectacular event which could therefore have made an impact on observers. Besides, according to some Chinese texts, two comets were visible to the naked eye in 5 B.C. and 4 B.C. But if the Christmas star was indeed a comet, why not describe it as such?The scriptures make clear reference to a star, discrediting the theory of the comet.

There remains the hypothesis of a conjunction: that is, the apparent convergence of two bodies in the sky. When two planets are practically in the same line of vision, the eye is no longer capable of distinguishing them, and only sees one object, but brighter. A simple astronomic calendar software enables us to see that during the year 7 B.C it was possible to observe, on three occasions, conjunctions between Jupiter and Saturn. These triple conjunctions are particularly rare. In the year 7 B.C., they happened on May 29, October 6 and December 1. At the time of the first conjunction, the Magi would have set off on their journey, at the second, they would have visited King Herod, and at the third, they would have been guided toward Jesus in Bethlehem. Should we celebrate Christmas on 1 December?

We are left with a fourth hypothesis, perhaps the most credible – the Christmas Star never existed and all this is just a charming legend.