From the off there's no talk of "wise men", "the three kings" or, as my daughter has been putting it, the "three wise king men". Instead the more accurate "magi" is used. There's a quotation from Philo, and some discussion about Zoroastrian astrologers. We go into the mistakes made by Dionysius in making the Gregorian calendar, and its implications - Jesus was born sometime before 4BC, and so we need to look for an astronomical event that occurred around then.
The first theory given is that the "star" was actually a comet. It fits the date but the portents would have been taken as a bad sign, it's popularity is simply put down to an early-ish Christian painting.
The next theory is that the "star" was a planet, but before fully explaining it there's a pause to look at who the magi were. Clarifying that they were not kings, but astrologers/astronomers, and suggesting that they came from Persia. There's an initially nifty effect here, highlighting a wall painting in the Roman catacombs, and converting the shadowy figures into Persian CGI characters. But the CGI characters are only marginally better fashioned than the catacomb sketches, and their overuse quickly begins to grate.
The theory itself is that the astronomical event in question was Jupiter and Saturn converging. This combined with their entry into the Pisces region in the sky, and their temporary reverse motion in the sky would have marked out a significant event. It not only fits the timescale, but also suggests the two phase movement from Persia to Jerusalem and then Jerusalem to Bethlehem. Astronomer Prof. David Hughes is to the fore here and even calls it his theory at one point.
The third theory is that a lunar occultation occurred and is championed by Michael Molnar. It's quickly passed over, without even taking time to explore some of its weaknesses. Instead we're introduced to Rick Larson who suggests that a copyist error has misdirected those looking for astronomical oddities in the pre-4 BC period. According to Larson, Herod actually died in 1 A.D. and just before this there is a convergence of Jupiter and Venus, and to top it all, the star stops on December 25. Again there's no counter evidence, but it all seems a little too like Larson had been trying to find the answers he'd already decided upon.
It's the proponent of the final theory, the European Space Agency's Mark Kidger, who does most to deconstruct all the theories above. Yes, Kidger argues, seeing these occurrences in the sky would be interesting and possibly even significant. But would they really be important enough to justify a 600 mile trip? Kidger argues not. Instead these events were just the warm up acts to the real "star" of Bethlehem, and it turns out that it's this fifth theory that is the attention-grabbing one mentioned at the start. But, disappointingly, it turns out that it's simply a dramatically bloated description of a supernova. The effects are similarly over the top as we see a CGI created exploding star again and again. And Kidger's theory comes across as no more plausible than any of the others.
Where Kidger is correct is that there were numerous such events in such a small timeframe which, in turn suggests that perhaps none of them were actually that significant. And the problem with this and a number of similar documentaries looking at the Star of Bethlehem is that they tend to completely overlook the possibility that the star was simply a literary device. It is, of course, entirely possible that the arrival of the magi made such an impact on Mary that this story was known in the early church. But it's also possible that Matthew was simply trying to make a statement about Jesus's significance - for example that he was lord over the rich and powerful, or ruler of the whole world. And regardless of the questions surrounding this event's historicity it's its symbolic significance that causes Matthew to include it in his gospel. After all, none of the other gospel writers see fit to include it (although it may not have been known to all of them). Furthermore this is the only group of Jesus's visitors that Matthew seeks to talk about, which raisies the question as to why he thinks this event is so significant.
Sadly the documentary is so caught up in its scientific speculation it fails to really tell us why Matthew thought it was important. And given just how... many... times it emphasises that astrology and astronomy were, at that time, essentially the same thing, it's certainly a most serious oversight.
Theological comments were provided by Joanna Jepson, Claire Foster, Phil Greetham and, to an extent I suppose, Rick Larson. Larson, David Hughes, Michael Molnar, Brian Cox, Richard Stevenson, Christopher Walker and Mark Kidger gave the astronomical information. Star of Bethlehem will be available for a few more days on BBC iPlayer for those in the UK.