Professor Colin Humphreys, University of Cambridge
Part of the show The Christmas Q & A Show
Chris - We're joined by Colin Humphreys from Cambridge University. Colin, you think that Jesus is going to have to move his birthday by about 5 years.
Colin - Yes I do. And I also think we're going to have to move Christmas to spring, as well.
Chris - So what's the basis for arguing that?
Colin - Well the key question is, What is the star of Bethlehem, which the gospels say was seen when Jesus was born? And I believe the star of Bethlehem was a comet, and we can look through Chinese records, we have detailed Chinese records. And the only star which fits, between say 20 B.C. and 10 A.D, that sort of period when Jesus might have been born, is a comet which appeared in 5 B.C. The Chinese records say it was a spectacular comet with a very long tail, and it lasted for 70 days. And I believe this was the star of Bethlehem.
Chris - Do you know what that comet could have been? Do we have any idea where it could have come from or how long it stuck around? Is it still out there somewhere?
Colin - Now that's a really good question. The answer is we don't know, because we need more observation. Some comets have elliptical orbits, like Haley's comet, which means it keeps coming back with a certain periodicity. But other comets are just a parabola, which is an open orbit. So you just see some comets once and that's it you never see them again.
Chris - So why do you think that this is a particularly strong contender?
Colin - I think this is a particularly strong contender because Matthew's gospel says the star stood over the place where Jesus was born. And lots of Christmas cards have sort of a star over a house. But what this means is, the Magi who were travelling from Jerusalem towards Bethlehem, they saw the star ahead of them standing over Bethlehem. And there's only one star which can seem to stand over a place and that's a comet. And a comet can appear to stand over a place because it has a long upward pointing tail, which points the head of a comet towards a particular place. And we have in ancient literature, two other examples of comet's standing over a place. Diocasius, a Roman historian, says that a star called Comet stood over Rome. And we can calculate when that was. That was in fact Haley's comet of 12 B.C. And Diocasius said this star stood over Rome. And then Joseph who was a Jewish historian, said a star shaped like a sword stood over Jerusalem. And in the ancient world, comets were often called swords because of their long tails. So we have two other descriptions of stars, we know both were comets and both of them were said to stand over a place. So when the Bible says this star stood over a place, I think it must have been a comet.
Chris - Would it have looked the same, wherever you were observing it from on the earth though? Because presumably the Chinese could see it, would it look the same from the Holy Land?
Colin - That's a really good question. So the place a comet appears to stand over depends on where the observer is. So a comet is low in the horizon, and when the Magi were travelling from Jerusalem to Bethlehem, they would have seen it appearing to stand over Bethlehem but actually it was many many miles away, low in the horizon. So it depends where the observer is.
Chris - What are the other contenders for the star of Bethlehem apart from your comet theory?
Colin - Well the most popular theory is a triple conjunction of Saturn and Jupiter. What's meant by a conjunction of Saturn and Jupiter, is when two planets are in line with the earth, so they all come together and they look as though they're just one planet. And that's a conjunction of planets. And in 7 B.C., this happened three times. So Saturn and Jupiter came together and separated, came together and separated, came together and separated. And that's the main contender for the star of Bethlehem. And the reason is, if you go back to what the astrologers believed, then Saturn was the father God, Jupiter was his Son. So when Saturn and Jupiter came together and separated, people have said a Son has been born to God. And the star background in the sky in which this happened, the constellation's name was Pisces, and the ancients mapped star backgrounds on to regions of the earth. And Pisces was mapped on to Israel in Babylonian astrology. So when you have Saturn and Jupiter coming together against a background of Pisces, the astrologers have said this means that a Son of God is being born in Israel. And lots of people think that's the star of Bethlehem. I think that was a precursor. I think that told them that something was going to happen. But the comet told them, it's happening now.
Chris - Obviously you've said that we may never see this comet again. Is there any way to prove your theory or is it going to have to remain just a conjecture which has some basis for it, along with many others?
Colin - There's certain things which suggest that this is really plausible. One is, you can say how do we know the Magi were interested in this triple conjunction of Saturn and Jupiter. Well we know they were because there's a place which is 30 miles north of Babylon that actually records this triple conjunction. It predicts it, they were pretty good astronomers. And so we know the Magi were interested in this triple conjunction. We also know that people are interested in comets, and another astronomer called Ptolemy, says "A comet in the east means an event is about to happen". So there's lots of things you can put together which suggest this. And the first writer that we know who identified what the star of Bethlehem may have been, writing in the 3rd Century A.D., a guy called Origin, he says "I believe the star of Bethlehem was a comet". So there's a lot of pointers that it really was a comet.
Dave - Mary and Joseph were meant to be going to a Census, to get written up. How does historical records of when they did Censuses relate to your theory?
Colin - Ok well the question of the census is a really good question, and this has puzzled people for a really long time. We have records of when the Roman censuses were. And there were none for that time, for taxation purposes. But another historian tells us that there was a census, not for taxation purposes but a census of allegiance. What happened was, the Roman emperor said "I want everyone to sign up their allegiance that they obey me as the Roman emperor". And the historian Josephus tells us that 5000 Jewish people didn't do this. And they were all slaughtered. So this could well have been the census. And from what Josephus writes, the census was in about 5 B.C.
Chris - That's Colin Humphreys from Cambridge University.