"The Christmas Star"

Every year I get a fresh round of questions about the Star of Bethlehem, the fabled celestial sign that led three wise men (read: astrologers) from Persia to a backwater town in Judea to hang out with the baby Jesus, his family, and - if manger scenes are meant to be taken literally - an assortment of farm animals.

Now I'm usually reluctant to answer this sort of question; any response I give that sits on the intersection of science and religious is often used as ammo to further one agenda or another. But in this case the answer is so deliciously unsatisfactory to all parties involved that I don't mind answering at all.

So let's get to it: looking at this story from the perspective of an objective astronomer, was there anything funky happening in the skies above the Middle East around two thousand years ago? Whatever happened had to be visible in the eastern skies from Mesopotamia and last a couple months, in order to support the wise dudes' trek.

A supernova would be a great candidate; they're sufficiently noteworthy and last several weeks. Unfortunately we don't have any records of ones appearing around that time. That doesn't rule them out, but the Chinese were fabulous notetakers of the night sky and we're pretty sure they would've caught it.

Halley's comet visited in 11 BCE, which is a tad early. Also, comets at the time were seen as Very Bad Omens - something to be avoided rather than chased. There are no convenient eclipses, either. But that's fine, since they don't last long enough anyway.

That leaves conjunctions, when planets happen to be close to each other on the sky. Those are pretty cool, and Jupiter and Venus were in conjunction in the eastern dawn sky in 3 BCE. The trouble with that is that King Herod - who the wise men visited - died in 4 BCE, so the timing is a bit off.

So there you go: something interesting did happen in the sky back then, but not quite at the right time. And that's all I can say.