THE STAR OF BETHLEHEM is getting its annual airing in the news. Here's a BBC article:

Star of wonder

By Rebecca Ellis

A comet, an eclipse, a supernova, an alignment of planets - was the Star of Bethlehem, said to have led the wise men to the Baby Jesus, a real astronomical event?

Some 2,000 years ago, wise men saw an incredible star shining over the Holy Land. It was their signal to embark on an epic journey to visit the new Messiah. But what exactly was the Star of Bethlehem?
Comet
... perhaps it was a comet

Modern science is unravelling the mystery behind one of the most famous astronomical stories in history. New developments in technology allow astronomers to map the ancient night skies with extraordinary accuracy.

As they study the movements of the planets and stars, experts are challenging the traditional assumption that it was a blazing comet - instead there are several unusual astronomical events that the wise men could have seen in the skies.

[...]

And that's pretty much where things stand. The scientific possibilities mentioned in the article include a planetary conjunction, a stellar-planetary conjunction, a supernova, and an eclipse of Jupiter. Physicist Frank Tipler has recently discussed the possibilities in his article "The Star of Bethlehem: A Type Ia/Ic Supernova in the Andromeda Galaxy?" in Observatory 125 (2005): 168-73. He thinks the supernova possibility is the most likely option and he lays out the conditions for testing the hypothesis.

Until and unless there's a scientific consensus on an astronomical event that fits the conditions at the right time, my working hypothesis is that the writer Matthew drew on or created midrashic traditions based on Balaam's prophecy in Numbers 24:17, which refers to a star coming out of Jacob. The passage was understood to have a messianic connotation in at least some ancient Jewish circles; for example, the title of the messianic leader Bar Kokhba (Aramaic for "Son of the Star") is based on this verse. A literal reading of it could have led to a story like the one we find in Matthew. But I see I've already noted this in a past post. Related posts are here and here. I've noted another cool Star of Bethlehem tradition here. And while I'm at it, I have posts on Matthew's Magi here and here.