This month the full moon falls on Three Kings' Day, traditionally a day that celebrates the adoration of the magi, so we investigate the famous Star of Bethlehem story. Through the centuries there have been dozens of astronomical and astrological theories put forward as to what the Star of Bethlehem was. We look at a few of the more prominent theories and their shortcomings, finishing with what is plausibly the leading candidate, the astrological theory of Michael Molnar, though as we'll see, this explanation, too, is not without its problems.

Transcript

Good evening, and welcome to the Song of Urania, a podcast about the history of astronomy from antiquity to the present with new episodes every full moon. My name is Joe Antognini.

Well this month the full moon happens to fall on January 6, which in the Roman Catholic Church is a holiday called Epiphany, but is sometimes colloquially referred to as Three Kings’ Day. These days Three Kings’ Day isn’t such a big holiday in the United States. Of course Catholics continue to observe it, but there isn’t much of a hullabaloo in the broader culture in the way there is for, say, Christmas. But throughout much of Latin America Three Kings’ Days is still just as big a holiday as Christmas. And even in the Anglosphere, back in the days of yore it was a much bigger holiday than it is today. Shakespeare wrote his play Twelfth Night as entertainment for the eve of the holiday, which is, not by coincidence, also called Twelfth Night. In fact, if you’ve ever wondered about that song that enumerates the twelve gifts for the twelve days of Christmas, in the Catholic liturgical calendar there is a period called Christmastide, which begins on Christmas Day and lasts twelve days, ending on January 6, or Three Kings’ Day, which commemorates the adoration of Jesus by the Magi. But historically the popularity of the holiday probably had more to do with the fact that Three Kings’ Day was your last chance to get in your Christmas fun before Christmas was officially over and you had to wait a whole other year for it to come around again.

At any rate, seeing as how today is Three Kings’ Day and in the last episode we talked about Roman astronomy up until around the turn of the millennium, it’s as good a time as any to talk about a rather unusual astronomical reference in the ancient literature that appears in the Roman Empire around this time — the so-called Star of Bethlehem that marks the birth of Jesus.

Now if there are any fellow astronomers listening to this who do planetarium shows, you’ll know that it’s obligatory to at least say something about the Star of Bethlehem in any show during December no matter how little one has to say on the subject. And so the Star of Bethlehem story has acquired the unfortunate acronym the SOB story. But I can assure you that I found working on this episode to be a delight, just as with any other episode. So this month I’ll walk through the documentary evidence we have for this story, and then go through the various hypotheses that have been proposed over the centuries to explain it.

Now just as a warning, this episode is somewhat fraught in a way that earlier episodes haven’t been. When I was talking about the astronomical diaries of the Babylonians or the planetary theories of Eudoxus, I’d like to think that the subjects were interesting at least from an intellectual standpoint, but, let’s be honest, at the end of the day, no one really cares. No one is going to get up in arms, literally or figuratively, about how to correctly interpret the Enuma Anu Enlil. But when we’re talking about the Star of Bethlehem, we’re now relying on texts which are today taken to be Holy Scripture by around one billion people, and that naturally invites a lot of strong opinions. And these come on both sides, from biblical fundamentalists who insist that every word of the Bible is literally true, but also from more militant atheists who assert that anything written in the Bible can be automatically dismissed as a fairy tale. But, regardless of your religious convictions, the Biblical texts are historical documents — maybe not historical documents quite like any other, though of course every document is unique in its own way. But just as with any historical document, it was written by a particular author in a particular place at a particular point in time and for a particular audience. If we understand that context we can hopefully understand which details in the narrative are more likely to have been real historical events, and which are less likely. And in the interest of full transparency on this topic, I’ll mention that I am a practicing Catholic, so take that for what it’s worth when assessing what I have to say about the topic. But needless to say, there has been a lot of flimflam written about this subject so we have to be careful when assessing sources.

Now there are four main texts which describe the life of Jesus, known collectively as the Gospels. One is attributed to St. Matthew, one to St. Mark, one to St. Luke, and one to St. John. Now, in all four gospels the primary focus of the text is on the torture and crucifixion of Jesus and his subsequent resurrection, so much so that the gospels are sometimes described as passion narratives with long introductions. Only two of them deal with Jesus’s infancy at all, the Gospels of Luke and Matthew, and both are relatively brief on the subject. Of these two, only the Gospel of Matthew describes the Star of Bethlehem. As I’ll get to later, the infancy narratives of Matthew and Luke are fairly complementary though in certain parts contradictory, and resolving these contradictions has bedevilled Christian scholars down the centuries.

Now today you can walk into any bookstore and choose from dozens of Bibles or go to thousands upon thousands of websites to read the Gospels in hundreds of different translations, from the old school Douay-Rheims or King James versions up to the Message, which translated the Bible into 1990s era American slang. But the ease with which you can look up any verse from any book of the Bible belies the fuzziness of the underlying texts. You’ll remember when I was talking about Greek astronomy, particularly early Greek astronomy, there was a tremendous difficulty in understanding what anyone thought because virtually all of the original texts had been lost. In the case of the Gospels we aren’t in quite as dire a situation, relatively speaking, but the word relatively there is doing a lot of work.

The unfortunate problem we have with the Gospels is that, although they are among the most important texts in Western civilization, the original texts do not survive. Nor do copies of the original texts survive. Nor do copies of copies of the original texts survive. It’s believed that the earliest surviving manuscripts are third order copies, that is, copies of copies of copies of the original, and were written at least a century after the originals, and even these are pretty fragmentary. Now this might not be a huge problem on its own, but unfortunately the copies were not perfect and so there is quite a lot of variation between the oldest versions, and this has led to a tremendous effort on the part of Biblical scholars to try to reconcile these differences. After all, if you are to believe that the Gospel represents the inerrant word of God, it is rather important that you figure out what exactly the text says.

Now it should be pointed out that while a lot of us would find this to be a rather self-evident proposition, this kind of obsessing over discrepancies between various manuscripts is in fact more of a modern concern. Up until the 17th century or so no one seems to have been much bothered by the discrepancies in the various Gospel manuscripts. For centuries, Bibles were produced by hand, almost exclusively by monks in monasteries. They would take an existing manuscript they had on hand and copy it out to make a second. Every now and again they’d make mistakes, but the copy would be a fairly close reproduction of whatever the original manuscript was. But this process was time consuming and expensive so Bibles were rare, and it was hard to get a whole bunch of manuscripts together to systematically assess their differences. But with the development of the printing press in the 15th century, Bibles started to be produced in much larger quantities. Initially, publishers would basically follow the same procedure that monks did, just at a larger scale. They’d take an existing manuscript, typeset it, and then make a bunch of copies. But in the 17th century, the Church of England commissioned the King James Bible, which was meant to be an authoritative translation of the Bible into English from the original sources, rather than from the Latin Vulgate which St. Jerome had produced back in the 4th century. But to come up with an authoritative version they had to make choices about what to print when the manuscripts disagreed with each other. Now the scholars working on the King James version were on a timeline so they had to make their choices quickly, but later in the century scholars like John Mill started to systematically try to assess the differences between the hundreds of known manuscripts.

Now the vast majority of the time these differences were minor. Sometimes you see manuscripts where the order of two words has been swapped, but it doesn’t change the meaning of the sentence, or other times there’s an obvious misspelling. But even then, there is, one apparent misspelling that has had a rather outsized impact. You may have heard the famous line from Matthew 19:24 in which Jesus says that “it is easier for a camel to go through the eye of a needle than for a rich man to enter the kingdom of God.” The Greek word for camel is kamêlos. But it’s believed that this verse is actually a misspelling in the early manuscripts of the word kamilos, where the e has been substituted for an i, and which means a thick rope or cable like you’d use to anchor a ship, and that makes a lot more sense in context. But the image of a camel trying to walk through the eye of a needle is just so vivid that it seems to have stuck.

Now again, the vast majority of discrepancies are minor, but there are still a couple of places where they would seem to be a pretty honking big deal. One of the better known scenes in the whole of the gospels is of Jesus with the woman caught in adultery which appears in the Gospel of John. The Pharisees bring the woman before Him and ask what should be done with her. The Mosaic law says that she must be stoned. Will Jesus condemn the woman to death, or will He contradict the law of Moses? Instead Jesus wriggles His way out of the trap and says to let he who is without sin cast the first stone. But popular though the story is, it did not appear in the original Gospel of John, it seems to have been accreted onto it a few centuries later.

At any rate, all this is to say that the texts of the Gospels, and indeed the rest of the Bible, are somewhat more fluid than we might otherwise believe. And the infancy narrative in Matthew where the story of the Star of Bethlehem appears is no exception.

Well, bearing all that in mind it’s probably best if I just read the relevant passage from the Gospel of Matthew that describes the mysterious star. In past episodes when I’ve had occasion to quote from the Bible I’ve generally used the more poetic Douay-Rheims version, but given that the Douay-Rheims version was written in the early 17th century, it can be a little hard to understand and being a fairly literal translation of the Latin Vulgate, it has some translation issues to boot. So I’ll use the Revised Standard Version Catholic Edition instead. So, here goes:

Now when Jesus was born in Bethlehem of Judea in the days of Herod the king, behold, wise men from the East came to Jerusalem, saying, “Where is he who has been born king of the Jews? For we have seen his star in the East, and have come to worship him.” When Herod the king heard this, he was troubled, and all Jerusalem with him; and assembling all the chief priests and scribes of the people, he inquired of them where the Christ was to be born. They told him, “In Bethlehem of Judea; for so it is written by the prophet: ‘And you, O Bethlehem, in the land of Judah, are by no means least among the rulers of Judah; for from you shall come a ruler who will govern my people Israel.’” Then Herod summoned the wise men secretly and ascertained from them what time the star appeared; and he sent them to Bethlehem, saying, “Go and search diligently for the child, and when you have found him bring me word, that I too may come and worship him.” When they had heard the king they went their way; and lo, the star which they had seen in the East went before them, till it came to rest over the place where the child was. When they saw the star, they rejoiced exceedingly with great joy; and going into the house they saw the child with Mary his mother, and they fell down and worshiped him. Then, opening their treasures, they offered him gifts, gold and frankincense and myrrh. And being warned in a dream not to return to Herod, they departed to their own country by another way.

Now this is not the only ancient account of the Star of Bethlehem. Although it doesn’t appear in any of the other canonical texts of the Bible, there are also dozens and dozens of Christian texts written in the centuries after Jesus which purported to be scripture, but which did not make it into the canonical Bible. These texts are generically referred to as apocrypha. Many of these texts had a particular theological axe to grind and were closely associated with sects like the gnostics that were later deemed heretical by the orthodox church. Others had no particular theological issues, but were rejected essentially because they were written by randos. The Church limited the canonical texts of the New Testament either to texts written by the apostles themselves, or by authors who were closely associated with one of the apostles. So the authorship of the Gospel of Matthew is, of course, traditionally attributed to the apostle Matthew, although modern scholars believe that Matthew himself did not write the text and that the author was an anonymous 1st century Jew. Although Luke was not an apostle he was a companion of St. Paul who was, so his text is effectively coming from Paul and made the cut.

At any rate there is another text called the Gospel of James which did not make it into the Biblical canon. Naturally it was attributed to the apostle James, but scholars of the early Church were not having it and decided that its authorship was inauthentic and they didn’t include it when they were compiling the Bible in the 4th century. Nevertheless, Christians of all centuries have been intensely interested in what the early life of Jesus was like, but the canonical gospels are pretty terse on the subject. The Gospel of James stepped in to fill that void and presented a more detailed narrative about Jesus’ infancy. Although it wasn’t canonical, there weren’t any major theological problems with it, in fact, if anything, some elements of it seem to have been included to counter certain heresies. There is a passage, for instance, in which Mary’s midwife, Salome, disbelieves that Mary is a virgin and so inspects her hymen and is astonished to find it intact, this being a repudiation of those who denied the virginity of Mary. In this story, Salome’s disbelief ends rather more poorly than that of the more famous doubter, Thomas’s, who demanded to stick his finger into the wounds of the resurrected Jesus or else he would not believe. Thomas suffered no ill effect except a rebuke from Jesus, but for poor Salome, after she has inspected Mary her hand fell off. But fortunately for her, God tells her to touch her dismembered hand to the infant Jesus, whereupon it is reattached.

Well despite its obscurity today, the Gospel of James ended up having a surprisingly large cultural impact. Much of the material in the Gospel of James was appropriated into a later apocryphal text called the Gospel of Pseudo-Matthew, and many of these stories in turn made their way into an extremely influential medieval text called the Golden Legend. If you look at nearly any painting of the nativity, you’ll see that there are three magi, and the day to celebrating them, 12 days after Christmas, was historically known as Three Kings’ Day. But when I read you the passage from the Gospel of Matthew, you may have noticed that there was no mention of how many magi there were! The original Greek text only says “magoi,” which just tells you that it’s plural, so all we can say for sure is that there was more than one of them. The idea that there were three of them specifically came from the apocryphal Gospel of James. Another common feature of nativity scenes in art, especially during the Renaissance is the presence of an ox and a donkey. This detail, too, derives from the Gospel of James.

Well the Gospel of James provides another description of the Star of Bethlehem. Much of the account is similar to that in Matthew, but the Gospel of James does add one detail about the star, saying that it shone with incredible brilliance and made the constellations seem dim.

So those are the texts we are working with. How are we to understand this tale? There have been dozens and dozens of explanations put forward in the two millennia since it was originally told, but we can group these explanations into four broad classes.

The first explanation is fairly simple. This is that the Star of Bethlehem was a true, real life, honest-to-John miracle. There was a miraculous star which led the magi from the east to Jerusalem and thereon to Bethlehem right to the manger where the infant Jesus lay. Probably if you surveyed Christians across the globe, this would be the favored explanation. And among many of the Church Fathers this was the preferred explanation as well. The earliest reference to it comes from St. Ignatius, who lived during the latter half of the first century and wrote that the light from the Star of Bethlehem was exceedingly great above all other stars and that “its novelty struck men with astonishment.” A few centuries later, St. John Chrysostom, the archbishop of Constantinople in the late 4th century, tried to make sense of the Star of Bethlehem story but found that only a miraculous explanation would work. After all, in the story the star leads the magi from Jerusalem to Bethlehem. And not just anywhere in Bethlehem, but some random barn, or at least some other equally humble structure, neither of the gospels actually describe the building that Jesus was born in, just that there was no room at the inn and he was placed in a manger. But if we’re thinking of the Star of Bethlehem as a literal star in the sky, how on Earth is it going to lead them directly to this itty bitty shed even if it is directly above it in the sky? It’s up so high that you could be anywhere in Bethlehem, or even Jerusalem for that matter, and the star would still appear to be directly overhead. So John Chrysostom argued that this must have meant that the star had somehow come down from heaven and was actually hovering a short distance above the manger. I think that would certainly qualify as a miracle. But there’s really not much more that I can say about this category of explanation because by definition, as a miracle, it cannot be understood in a scientific or historical framework.

The second explanation is fairly simple as well. In this explanation, the story is a pious fable, a charming tale that the author made up out of whole cloth. Perhaps it allegorically illustrates some deeper theological points, but as a matter of history, there was no Star of Bethlehem, nor were there any magi. Probably most people who are not Christian would take this position by default. If you don’t think that the Star of Bethlehem was a miracle, it’s an explanation that is pretty compelling. First of all, the Star of Bethlehem as it is described in the story is just very hard to understand as a physical phenomenon. The magi are off to the east, probably in Persia, and then they see this star to their east, but then they go in the opposite direction, west towards Jerusalem. How can the star be leading them towards Jerusalem if Jerusalem is to the west and the star is in the east? Then there is the whole matter of the star leading them from Jerusalem to the little town of Bethlehem to the south. This, too, is hard to understand. Over the course of a night, stars rise in the east and set in the west — they travel from east to west. But somehow after the magi visited the court of Herod in Jerusalem, this star has led them from north to south. Then there is a sort of meta-problem with the whole Star of Bethlehem story, namely that Judaism has always been suspicious of astrology — the Mosaic law prohibits divination and generally astrology has been associated with divination. So what is a story like this doing in the Bible?

And it is not as though this is the only difficulty in the infancy narratives. If the only description of the birth of Jesus was in the Gospel of Matthew, well, we’d still have a couple of problems understanding the Star of Bethlehem, but we wouldn’t have too many issues with the overall structure of the narrative. But the fact that we get accounts of the nativity of Jesus in two Gospels presents a much bigger problem. It’s very hard to reconcile even the more basic points of the narrative between the two gospels. Both gospels include a genealogy of Jesus — Matthew going forward in time starting with Abraham, and Luke going backwards in time starting with Jesus and going all the way back to Adam. Now the reason the two do this is because the prophecies of the Messiah were clear that he was to be a descendent of King David, and so both Luke and Matthew duly show that Jesus is indeed a descendent of King David. But the two gospels disagree with each other about everyone in between David and Jesus’s father Joseph.

The infancy narratives themselves have different emphases, which is not a problem in itself. Matthew focuses more on Joseph whereas Luke focuses more on Mary. But on the points that touch on both of them, like where the Holy Family was at different points in time, it’s hard to put them together in a cohesive way. In the way Matthew tells the story, Jesus was born in Bethlehem, and at some point the magi came from the East to the court of King Herod, learned of the Jewish prophecies specified that the Messiah was to be born in Bethlehem, and then payed homage to the child in Bethlehem. Afterwards King Herod attempted to have the boy killed as a potential rival to the throne and the Holy Family escaped to Egypt. Once King Herod died a few years later and was replaced by his son Archelaus, Joseph felt that Bethlehem still wasn’t safe, and so resettled in Nazareth to the north. In Luke’s telling, Mary and Joseph are living in Nazareth all along, but then Caesar Augustus declares a census and everyone has to go to their hometown, which in the case of Joseph, is Bethlehem. Because everyone was in town for the census, there was no room at the inn and Jesus had to be lain in a manger. Afterwards, Jesus was presented at the temple in Jerusalem in accordance with the Mosaic law which would have been 40 days later, and then the Holy Family returned to Nazareth. So in Matthew’s telling they start out in Bethlehem, flee to Egypt for some period of time, probably a few years, and then move to Nazareth. And in Luke’s telling they go from Nazareth to Bethlehem, stay no more than 40 days, go to Jerusalem, and then head back to Nazareth.

Now, perhaps this is not an insurmountable contradiction. The gospels are fairly terse and so a fair amount has to be read into the text. But whenever you do this, you might be making assumptions which are not warranted. For example, the first place that Matthew’s gospel mentions is Bethlehem, and says that Jesus was born there. So if you read that you naturally assume that that’s where Mary and Joseph were all along. But it’s perfectly consistent with the text that the Holy Family started out in Nazareth and then went down to Bethlehem for the census just as Luke described, but Matthew didn’t bother including it. But then how do you square Luke’s version of events where they almost immediately leave for Jerusalem and then on to Nazareth with Matthew’s version where they flee to Egypt for a few years? Over the centuries various commentators have tried to reconcile these stories by supposing that the Holy Family went to Jerusalem to present Jesus in the Temple 40 days after his birth as was required by Mosaic law, but then they go back to Bethlehem, flee to Egypt as Matthew says, and later return to Nazareth, but Luke just omits all those parts. But I think it has to be admitted that harmonizing the texts like that is not the most natural reading of either of the texts in isolation.

A more serious issue arises when we try to link this story to the broader historical context. Now, one of the nice things about the Gospels is that they are full of historical details that are possible to independently confirm or deny. As CS Lewis put it, “anyone who thinks that the gospels are a myth hasn’t read a lot of myths.” The gospels contain a number of details which help us to cross reference the events they describe with the rest of the world. This is critical for establishing the years of Jesus’s birth and death, which, after all, forms the reference point for our system of counting the years.

There are a few main details that the gospels provide. In Matthew we hear that Jesus was born during the reign of Herod and that Herod died a few years later. Now unfortunately we don’t know exactly when Herod died, but 4 BC is the most likely year. The Jewish historian Josephus wrote that there was a lunar eclipse just before Herod’s death and that he died before Passover of that year, and in the 4 BC there was a lunar eclipse on March 10 and Passover was April 10. Furthermore other records say that Herod’s sons Archelaus and Philip the Tetrarch began their reigns in 4 BC. But some historians dispute this evidence — the lunar eclipse was just a partial eclipse and Archelaus was almost certainly exercising royal power while Herod was still alive. So 1 BC or 1 AD are also taken to be possible dates of Herod’s death. But if the Gospel of Matthew can be believed, this would place the date of Jesus’s birth about two to four years earlier, or sometime between 8 and 6 BC. But then there’s the matter of the census in Luke’s account. Luke says that this was undertaken while Quirinius was the governor of Syria. Now Syria was a rich province in the Roman Empire, so Quirinius was quite an important man in his day and we know independently that he became governor in 6 AD. Now the census Luke describes really did happen — it was common practice when a new governor assumed his office that he would conduct a census of the province to figure out whom he was ruling over. So if Jesus was born during the census as Luke describes, this would place his birth at 6 AD, 10 years after Herod died, which is in contradiction to Matthew’s account. So as you start to pick apart these two accounts you start to see the problems pile up around you and it’s natural at a certain point to throw up one’s hands and just declare that the whole thing was made up and that there’s no use trying to make any sense of it.

So that is the second category of explanation of the Star of Bethlehem, the “pious fable” explanation, and it is, I think, fairly compelling, and for a lot of people it would take a great deal of evidence to demonstrate that it is wrong. But I think it is too easy to just dismiss the Star of Bethlehem story out of hand without putting in a little effort to see whether or not there could have been some possible alternative explanation. After all, even if there are some contradictions in the texts, it is certainly the case that portions of the texts are rooted in history — Herod really did exist and Quirinius really did conduct a census. While it’s maybe the case that these historical events got woven into the infancy narrative in an incongruous way, just because Luke describes a census of Quirinius that doesn’t make sense chronologically with Matthew’s account doesn’t mean that the census of Quirinius didn’t actually happen. So maybe it’s the same with the Star of Bethlehem — maybe there was some real celestial event that occurred around that time which got woven into the infancy narrative. Any other problems or contradictions we see in the texts don’t really refute that possibility.

So, we’ll move on to the last two categories of explanations which are better suited to the subject of this podcast: that the Star of Bethlehem was an astronomical phenomenon or that it was an astrological phenomenon.

Now, perhaps for obvious reasons, astronomers who want to entertain the possibility that the Star of Bethlehem had its roots in a real physical phenomenon have overwhelmingly preferred astronomical explanations. And in some ways this makes sense. In the last 150 years our understanding of the physical universe has grown in ways that would have been unimaginable to the ancients — modern day astronomers have a detailed understanding of all sorts of transient phenomena that were either mysterious like comets, or totally unknown like novae and supernovae. So, having a knowledge of modern day astronomy can feel a little bit like having a decoder ring. We more or less know all of the naked eye phenomena that can be seen in the skies, so it is just a matter of figuring out which one is consistent with the details of the text and independent historical records.

One possibility that was explored early on was Halley’s comet, which is a short period comet with a period of about 75 years. Being very bright and with such a short period, Halley’s comet has been a frequent interloper on human events, seen in 1066 as an omen for William the Conqueror’s victory at the Battle of Hastings, in 1222 as an omen of the invasion of Europe by Genghis Khan, and in 1456 as an omen for the invasion of Hungary by the Ottoman Empire. And if we wind the clock back, Halley’s comet made an appearance in 12 BC. A Roman historian by the name of Cassius Dio recorded it and said that it was an omen of the death of Marcus Agrippa. Now, one problem with Halley’s comet as the Star of Bethlehem is that 12 BC is just a smidge too early to really be a contender. The story does seem to indicate that the Star of Bethlehem was around in the sky when Jesus was born, and the earliest He could have reasonably been born is 8 BC, four years after Halley’s comet had made its appearance.

There was, however, another comet which appeared in 5 BC. Now this comet was not recorded anywhere in the West, unless it was the Star of Bethlehem, but Chinese astronomers kept detailed records of the night sky and noted when new stars appeared and had a list of descriptors that they would apply to these new stars. Comets would generally be given the name “broom stars” because the tail gives the comet the appearance of a broom. At any rate, the Chinese astronomers recorded one such broom star in the spring of 5 BC which would coincide well with the timing of Jesus’s birth.

Now the hypothesis that the Star of Bethlehem was a comet has a few points in its favor. First, we know that a comet actually did appear. Second, Matthew describes the star as having been seen twice, once when the magi set out from the East, and then again when they leave Jerusalem to go to Bethlehem. And comets are often seen twice, once when they are heading towards perihelion and again after they have gone around the Sun and are moving away from it. Furthermore, the text describes the star as “hanging over” Bethlehem and this phrasing is almost exclusively applied in the ancient literature to comets.

But there are a couple of problems with this explanation as well. The main one was maybe already evident when I went through some of the ways that Halley’s comet has been interpreted over the years. The Romans saw it as an omen of the death of Marcus Agrippa, later on it was seen as an omen of the invasion of Genghis Khan and the Ottoman Empire. Almost universally, comets have been interpreted as omens of doom and destruction. In fact the whole reason that Chinese astronomers were making detailed records of comets in the sky was as a sort of early warning system for the emperor. So why would this comet in particular, which otherwise does not seem to have been notable, have been interpreted by the magi as the sign of the birth of a great king? I suppose you could make the argument that from the perspective of the Persians, the rise of a great king in Judea would have been bad news for them, so maybe they decided to curry favor with this new king right from the start just in case. But it’s a bit of a stretch.

There’s a similar vein of explanations which tries to associate the Star of Bethlehem with a nova or supernova. Again, here if we turn to Chinese records, we see that there was a new star recorded in the late winter of 4 BC. Now, historically, most supernovae recorded by Chinese astronomers were described as “guest stars” because they were pointlike. This one is described as, and you’ll have to forgive my pronunciation, “po-hsing.” The second word “hsing” means star and the first, “po” roughly translates to “light shooting out in all directions,” which is a little awkward in English and so instead typically gets translated as a “scintillating” or “sparkling”. These objects are only recorded every 40 years on average, so their relative rarity may indicate that they were especially bright. Furthermore, this particular object was recorded to be in the modern-day constellation of Aquila. If you were standing in Jerusalem around the time it appeared in the sky, at sunrise this scintillating star would have been in the direction of Bethlehem. Now what exactly the scintillating star of 4 BC was is unclear. Sometimes objects described as scintillating stars turned out to be comets, other times novae, and other times supernovae. There is no clear candidate, though of course astronomers have made a number of proposals over the years.

Now I think that all the astronomical explanations for the Star of Bethlehem suffer from a couple of very serious flaws. I’ve already mentioned that the comet hypothesis suffers from the problem that the magi took the star to be a sign of the birth of a great king but comets were universally regarded as harbingers of doom. And taken more broadly, this issue is a problem with all astronomical explanations. They might demonstrate that there was something unusual in the sky in the time period we’re looking at, but they tell us nothing about how the magi in the story would have interpreted them. Suppose that the star was a comet or a supernova. The magi apparently saw it in the east — why did they decide to travel to the west? How did they know that this heralded the birth of a great new king? Furthermore, comets are relatively common. The journey from Persia to Judea was long, probably taking about a month — it would seem that whatever they saw in the sky would have had to have been really quite spectacular for them to have bothered to make the journey. And while the Chinese records show that there was a comet here and a nova of some kind there, astronomically, the years just prior to Christ’s birth aren’t especially notable. Purely astronomical explanations for the Star of Bethlehem tend to have to handwave these issues away.

And more to the point, the premise of these kinds of explanations just does seem seriously flawed right from the get-go. It does us no good to try to understand this object as 21st century astronomers. We can’t point to some astronomical phenomenon, however unusual, and just suppose that that must have been the Star of Bethlehem because it happened to occur during the handful of years we’re interested in. Not to belabor the point, the things that we moderners consider to be spectacular celestial events are not necessarily the same things that the ancients considered to be spectacular celestial events.

So this leads us to the final category of explanations: astrological explanations. Now as I mentioned earlier, astrological explanations do fit in sort of awkwardly to the broader Biblical narrative. The Mosaic law is generally hostile to astrology and indeed all forms of divination. Nevertheless, given that astrology has always been popular among the masses, the Catholic Church later on had to introduce a distinction between astrology that attempted to divine the future, which was forbidden, and astrology which merely tried to study the influence of the heavens on the Earth. Since the planetary influences could be overcome by one’s own free will, this form of astrology was deemed acceptable. At any rate, if the Star of Bethlehem was astrological in character, it does seem a bit odd that Matthew even pointed it out. It’s worth pointing out here, too, that there is another unusual feature of the Star of Bethlehem in the Gospel narrative. Later commentators were quick to draw the connection between the Star of Bethlehem and a line all the way back in the book of Numbers in which a diviner by the name of Balaam says “a star shall come forth out of Jacob, and a scepter shall rise out of Israel,” and this was later called the Balaam prophecy. Now if you know the Gospel of Matthew you’ll realize it’s strange that he did not seem to make this connection. Every chance he gets, Matthew jumps at the opportunity to let you know when Jesus has fulfilled a prophecy, saying something like “thus was fulfilled what was spoken by the prophet” so-and-so, and then he’ll quote the relevant verse. In fact in the short passage I read earlier in this episode he did that when he specified that the prophecy was that the Messiah would be born in Bethlehem. And in the subsequent two paragraphs he does it twice more, once for the flight to Egypt and once more for the massacre of the innocents. But for the Star of Bethlehem Matthew somehow doesn’t make the connection to the prophecy of Balaam. Perhaps this is the exception that proves the rule. If this sign was of an astrological character, he may not have wanted to call too much attention to it as fulfilling a specific prophecy lest it be read as condoning astrology.

Well the oldest astrological explanation dates back to the late 8th century BC and is due to the Jewish Persian astrologer Masha’allah. Masha’allah wrote a number of texts which generally don’t survive, but one of these was entitled On Conjunctions and some fragments of it were quoted in a later work which did survive. The main idea of the work seems to have been to present an astrological history of the world based on conjunctions between Jupiter and Saturn. Of the five classical planets, conjunctions between Jupiter and Saturn are the rarest owing to the fact that they move the slowest in the sky and consequently they have come to be known as Great Conjunctions. Saturn has a sidereal period of about 30 years and Jupiter about 12 and if you do the math, Jupiter ends up overtaking Saturn roughly once every 20 years. Masha’allah seems to have associated these conjunctions with great events in world history, from the great flood described in the Book of Genesis to the birth of the prophet Mohammed. But one of the events marked by a Great Conjunction that Masha’allah notes is the birth of Jesus since there was one of these conjunctions in the year 7 BC.

This theory was revived in the 17th century by the German astronomer Johannes Kepler. Kepler had noticed that because Saturn’s sidereal period is about 30 years and the interval between Great Conjunctions is 20 years, each successive conjunction happens about 240 degrees away from the previous one, or, going in the other direction, 120 degrees away. So after three conjunctions, the fourth would be about 360 degrees away from the original one, or in other words, it would be in approximately the same place. So if you drew a circle to represent the zodiac and then points at the locations of successive Great Conjunctions and then drew a line connecting them, you’d get an equilateral triangle. Or at least, you’d get approximately an equilateral triangle. The intervals between Great Conjunctions don’t exactly work out that the fourth Great Conjunction will be precisely the same spot as the first, it will be shifted by around 10 degrees. So if you plot the locations of Great Conjunctions and connect them by lines, you get a picture of a slowly rotating equilateral triangle.

Now this diagram fascinated Kepler and it became the inspiration for his entire line of astronomical research and I’ll get into it in much more detail once we get to the astronomy of early modernity. But for our purposes, one of the things that Kepler noticed about this diagram was the zodiacal signs that each conjunction appeared in. One of the features of Western astrology going all the way back to Ptolemy is the concept of a trine. These are sets of three zodiacal signs 120 degrees apart on the sky and each set is associated with one of the four classical elements. So for example the signs Aries, Leo, and Sagittarius are associated with the element fire. Kepler noticed that if you look at the signs that Great Conjunctions appear in, they all appear in the same trine for about 200 years. So the conjunctions will bounce between, say, Aries, Leo, and Sagittarius every 20 years and after 10 of these conjunctions, the equilateral triangle connecting them will have finally rotated out of that trine and into a new trine with a new set of astrological associations. Since there are four trines in all, this meant that after 800 years the entire cycle would repeat itself.

Well, about a decade after studying these diagrams, Kepler found himself in the court of the Holy Roman Emperor Rudolph II initially as an assistant to Tycho Brahe. But Tycho died less than a year after Kepler joined him and subsequently Kepler became the imperial mathematician which in practice meant that his principal duty was to provide astrological advice to the emperor.

In late 1603 Kepler observed a Great Conjunction but this was a very special one because it was the first conjunction to occur in a fiery sign in some six hundred years. Less than a year later there was a conjunction between Mars and Saturn and then a conjunction between Mars and Jupiter a few weeks after that. Then just a few weeks later an excited court official ran to Kepler just after dawn and told him that although the night had been mostly cloudy, there had been some gaps in the clouds and he had seen a bright new star in the sky. Kepler was dubious and naturally wanted to see for himself but unfortunately the next few nights were completely clouded out. But when the sky cleared up a few days later Kepler was able to verify that there was, indeed, a new star in the sky in the constellation Ophiuchus. The new star was bright enough that it could even be seen, faintly, during the day and we now know that it was a supernova in the Milky Way, and in fact was the most recent supernova to have occurred in our own galaxy.

Well this series of events seemed like it could be no coincidence to Kepler. Here we had a once-in-800 year event as the Great Conjunctions shifted from the watery trigon to the fiery trigon, followed by the appearance of a new star in the sky, something that, while not totally unprecedented since Tycho had seen a new star a few decades earlier, was at least exceedingly rare. Kepler put two and two together and hypothesized that the movement of the Great Conjunctions into the fiery trigon was what caused the new star in the sky. Since all signs pointed to this being a tremendous omen, Kepler went back through history to see what this had portended. He made a little table in which he wrote down the years when a Great Conjunction first reentered the fiery trigon and found that 800 years earlier corresponded to the time of Charlemagne, and 800 years previous to that corresponded to the birth of Christ. Going back further was the birth of the prophet Elaias, then Moses, then Noah, then Enoch, and finally Adam at the beginning of time. As a savvy courtier, into that mix of Charlemagne, Moses, and Jesus Christ, for his own age, Kepler listed his employer Rudolph II. Then Kepler also went forward one cycle to the year 2400 and somewhat wistfully writes “Where will we be then, and will anyone remember us Germans?”

Well Kepler’s association of the fact that there was a Great Conjunction entering into the fiery trigon around the time of Christ’s birth was just a preliminary result, a kind of back of the envelope, order-of-magnitude calculation. He knew that the cycle lasted about 800 years and because the Great Conjunction was entering into the fiery trigon around 1600, this would have meant that it would have also entered into the fiery trigon about 1600 years earlier, sometime close to the birth of Christ. So Kepler went to work to make a more detailed calculation here to find the closest Great Conjunction. Now, given the state of astronomy at the time, doing this accurately so far back in the past was quite challenging, and Kepler’s results were off by about two degrees. But the main thing he found was that there was a Great Conjunction in the year 7 BC, and not only that, it was a triple conjunction. Jupiter moves faster on the sky than Saturn does, so in a normal Great Conjunction, Jupiter simply catches up to Saturn, they’re close together on the sky, and then they start to drift apart. But sometimes this happens around the time that Jupiter is in opposition. Then, Jupiter catches up to Saturn and there is a conjunction, it keeps going for a little while, but then it stops and enters into retrograde. It moves backwards and meets Saturn again to produce a second conjunction, and then continues to move backwards. Then the period of retrograde motion ends and it begins moving forward again, and then catches up to Saturn one last time for the final conjunction. Well it turns out that the Great Conjunction a few years before the birth of Christ was one of these triple conjunctions, which seemed especially auspicious to Kepler. But there was one problem — all these conjunctions were in Pisces which is a watery sign. His theory was that the sign of the birth of a great leader came when the conjunction entered into a fiery sign. But Kepler kept looking and found that shortly after this triple conjunction, there were two further conjunctions — in the year 6 BC, Mars caught up to Saturn and then a month later it caught up to Jupiter. This last conjunction was in Aries which was indeed a fiery sign. So it seemed, according to Kepler, that as long as one of the conjunctions in this series progressed into a fiery sign, this would be sufficient to mark the astrological sign of the birth of a great leader. Moreover, Kepler drew a connection between the new star seen after Great Conjunction of his time and the Star of Bethlehem. Kepler’s theory was that the entrance of a Great Conjunction into the fiery trigon produced a new star in the sky. He had seen this in his own time, and he believed that the Star of Bethlehem recorded in the Gospel of Matthew was evidence of another such new star in the past.

Now Kepler is the only one who seems to have seriously entertained the idea that the conjunction itself produces a nova. But the idea that the Star of Bethlehem was the Great Conjunction of 7 BC did persist for several centuries. The idea has a few things going for it — Great Conjunctions are intrinsically pretty rare — they only happen a few times in someone’s lifetime. And triple conjunctions are rarer still. But the main problem that the idea has is that there’s no evidence that ancient astrologers really cared very much about them. The astrological significance of the Great Conjunction only developed in the Middle Ages. So, rather like astronomical explanations, the hypothesis that the Star of Bethlehem was a Great Conjunction seems to be rather anachronistic.

So this leads us to the last idea that I’ll discuss, which was proposed by the astronomer Michael Molnar in the 1990s and which I would consider to be the leading candidate of an explanation for the Star of Bethlehem, though, as we’ll see, it’s not without its problems. Molnar’s idea originally derived from a hobby of his, which is collecting ancient Roman coins. Many of these coins have astrological symbols depicted on them and Molnar noticed that coins that were minted in Syria had a ram with a star. This observation helped him develop a theory that addressed one of the principal shortcomings of other theories of the Star of Bethlehem.

As I’ve mentioned earlier, one of the main puzzles in the story is that it says that the magi observed the star in the east, and then went to Jerusalem, which was in the west. Clearly they were not just walking in the direction of the star. So what about this object told them to go to Jerusalem? Molnar argues that we have to understand this event astrologically. The text uses the word “magoi,” which strictly speaking meant a Zoroastrian priest, but at the time it was commonly used as a generic term for an astrologer. So, if we want to understand how astrologers of the time thought, we have to turn to the closest contemporary source on astrology. This would be Ptolemy’s Tetrabiblos, which I described two episodes ago, more briefly than I would have liked, but in my defense there was a lot to say about Ptolemy. Now, it’s true that the Tetrabiblos was written in the mid 2nd century, so about 150 years after the Star of Bethlehem appeared, but it is the best and closest source available so it’s what we have to work with.

Now in my short summary of the Tetrabiblos I talked a little bit about one subfield of astrology, which is known as astrological geography. The idea is that different regions of the world are assigned to different zodiacal signs and are influenced differently by the heavens. I mentioned that in Ptolemy’s division of the world, the northwestern region, containing Spain and Britain, was dominated by Mars and Jupiter, and as a consequence produced a highly masculine and domineering people who had a low regard for relationships with women. Well in his discourses on astrological geography, Ptolemy assigns the region of Syria to the sign of Aries, along with several neighboring countries, including Judea, and he says that this association makes the people of that region bold, godless, and scheming. The association of Syria and its surroundings with Aries does not appear to be unique to Ptolemy — there are the Roman coins, of course, but other later astrologers like Vettius Valens, who was a generation after Ptolemy, also assigned Syria and its surrounding lands to Aries, though, in his case he did not explicitly mention the kingdom of Judea. So, if the Star of Bethlehem was an astrological omen in the sign of Aries, this would explain why the magi saw it in the east and then went west. Now one issue we have here is that the magi went to Jerusalem specifically, but the sign of Aries covers all of Syria. Syria at the time was a very rich province of the Roman Empire, so if the magi saw the sign and decided to go to the most prominent city in the region, they presumably would have gone to a more important city like Damascus. What caused them to go to the less important city of Jerusalem is unclear. But in its favor, this explanation undercuts both the pious fiction and miraculous explanations. If Matthew was just making up the story or if it was a genuine miracle that was leading the magi to the infant Jesus, why did the star not just lead them directly to Bethlehem? Why did they have to first go to Jerusalem? But if this was an omen in the sign of Aries it becomes clearer. The magi knew the association of Aries with Judea and went to its capital. There they inquired in King Herod’s court and learned of the prophecy that the messiah was to be born in Bethlehem, so they then traveled along to that town.

OK, so what was this omen in Aries that motivated the magi to spend a month traveling from Persia to Judea? Molnar’s theory is that it was what is called a “massing” of the planets on the 17th of April in 6 BC. At this time, all the planets, at least all the classical planets, were bunched up very close to the Sun in a particular configuration. To understand the significance of this we’ll have to go into a little more detail about how Ptolemy’s astrology worked.

Earlier when I was talking about Kepler’s idea of the fiery trigon I mentioned the idea of the trine. The zodiac was divided into four sets of three signs called trines. Each sign in a trine was 120 degrees apart from the others and formed an equilateral triangle and each set was associated with one of the four elements of fire, water, earth, and air. So for example the fiery trine was Aries, Leo, and Sagittarius, and the watery trine was Cancer, Scorpius, and Pisces. Each trine had a set of three planets associated with it and these planets were ranked in order of their power in the trine. Furthermore there were actually two separate rankings, one which was effective during the day, and another which was effective during the night. The planets in the lists were the same in both cases, but the order was different. So, for example, in the fiery trine, the Sun took precedence during the day, but Jupiter took precedence during the night.

Now all of the planets had an astrological association — Jupiter was, for example, a regal planet, associated with kings. Mars was an evil planet, associated with war and destruction. When a planet entered into a sign in its trine, its astrological effects were amplified, but if it was not in one of its trines its astrological effects would be weakened. But to make things more complicated, in Ptolemy’s astrology the planets did not act in isolation, they interacted with each other. If one of the opposing planets like Mars or Mercury was 90 degrees away from another planet, a configuration called a quartile, this would counteract the impact of the planet. By contrast the Moon acted as a sort of magnifying power. If the Moon came in conjunction with a planet, and especially if it occulted the planet, that is, passed directly in front of it, it would enhance the astrological influence of the planet.

Well on April 17 in 6 BC Jupiter had its heliacal rising in the sign of Aries. I’ve mentioned heliacal risings on a number of occasions, but as a reminder, in general the stars, along with the superior planets drift east to west with respect to the Sun, or, more properly, the Sun moves west to east with respect to the background stars, as do the superior planets, just more slowly. As the Sun gets closer to a planet or background star, the star will only be visible briefly after sunset low on the western horizon. Then, when it gets too close to the Sun, there will be a period of time where it’s not visible at all. But eventually the Sun will continue to drift and the planet or star will reappear by rising in the eastern sky just before dawn. Astrologically a heliacal rising had associations with birth, since it appears that the star is rising up from the Sun and then it lives its life in the sky for the better part of a year before its heliacal setting where it seems to be extinguished by the Sun once again. So, when the magi say that they have seen a star in the East, the most natural reading of this is that they had observed a heliacal rising. And a heliacal rising of Jupiter, in particular, being the regal planet, would have signified the birth of a king. So, so far in Molnar’s theory, on April 17 of 6 BC we have a heliacal rising of Jupiter in Aries, which would portend the birth of a king in Judea.

But it’s not enough to just know that a king would be born. The rest of the planets have to be taken into account to read the horoscope. Here, all the signs pointed to this being an exceedingly auspicious horoscope. Jupiter was rising in Aries and what’s more there was an occultation with the Moon, which would have magnified its powers. Just to the west was Saturn and then Venus. Saturn was associated with the fiery trine which included Aries, so this further increased the power of the trine, and Venus was just outside of Aries in the sign of Pisces, part of the watery trine that it was associated with. Since Venus was also an exalted planet, seeing it both in its own trine and close to the Sun and Jupiter was a very auspicious omen. Then, just to the east of the Sun, and so not visible before dawn, were Mars and Mercury, two planets with malevolent associations. The whole configuration, then, had the form of a sort of regal procession, beginning with Venus in its trine, moving on to Saturn in its trine, followed by Jupiter in its trine at heliacal rising, and culminating in the Sun, also in Aries, where it, too, had strong associations. And with Mars and Mercury taking up the rear, they were acting as a sort of rear guard and did not have the destructive aspects that they would if they were 90 degrees apart from the configuration in quartile. So all in all this was an extremely auspicious royal horoscope.

As evidence for the plausibility of this reading, Molnar has pointed to a similar horoscope that was drawn up for the Emperor Hadrian by the astrologer Antigonus of Nicaea. Hadrian was born on January 24, 76 AD and on this day there was a similar kind of massing of the planets, though this massing was not quite as compact as the one in 6 BC. But the important thing that Antigonus pointed to was that Jupiter was in its heliacal rising, or nearly so anyway, and was in conjunction with the Moon. And furthermore, the other planets were close to the Sun and in signs that they were associated with — in their own houses to use the astrological terminology. So in many ways the horoscope for Hadrian was similar to the one in 6 BC, though somewhat less powerful since the Jupiter wasn’t quite in its heliacal rising for Hadrian and the Sun was in Aquarius, which was part of a trine it was not associated with.

At any rate, the horoscope of April 17, 6 BC seems to have been extremely auspicious, so the idea is that astrologers in Persia would have either seen it directly or predicted it some time in advance from astronomical tables. Knowing that Aries was associated with Judea, they then would have deducted that this portended the birth of a great king in Judea and they then would have traveled to Jerusalem to investigate. Now it’s worth asking, just how rare was this particular configuration of stars? From one perspective it was exceedingly rare — this exact configuration would only come about once every three millennia or so. But that’s not quite the right way to look at it because there are surely other configurations that would produce similarly auspicious horoscopes. Astrology is by definition not an exact science, so quantifying the rarity of a horoscope like this is a squishy business. Nevertheless, at least according to astronomer David Hughes a propitious horoscope for a king of Judea of this magnitude would plausibly only come about once a century or so or maybe once every few centuries. So something like this would have grabbed the attention of the magi.

One other detail that Molnar’s theory attempts to grapple with is that after leaving Jerusalem to go to Bethlehem, Matthew says that the magi saw the star again and rejoiced greatly. In Molnar’s theory, about eight months after the initial massing, Jupiter had started to travel out of Aries, but then went into retrograde motion and remained stationary in its own house, which was also an auspicious omen for Judea. This loosely ties in to the wording of Matthew’s account, that first the star “went before” the magi and then that it “stood over” the child. Now one of the points of criticism of Molnar’s theory is that Greek had specific terminology for these kinds of astrological events, the heliacal rising, prograde motion, the stationary point, and Matthew does not use those terms. But I think it’s plausible that we might be expecting too much of poor St. Matthew. After all, he was a first century Jew and his intellectual environment was as a rule hostile to astrology. So it’s not entirely unreasonable that he would have been unfamiliar with the astrological jargon of his day and may have been trying to describe an event he lacked the language for. We’re not terribly surprised today, for instance, when on occasion we hear intelligent people like appellate court justices or history professors mangle references to quantum physics when they’re reaching for an analogy.

Now this theory has the benefit of explaining another detail in the original text. Matthew says that after the magi arrive in King Herod’s court and tell them of the sign they had seen of the birth of a king of the Jews, King Herod was troubled and all Jerusalem with him. Now it is maybe reading into the text a little bit, but the implication here is that King Herod, along with all of Jerusalem are surprised by this revelation from the magi. At a minimum, whatever had happened in the sky, they were clearly unable to interpret it on their own. Now if an astronomical or miraculous explanation were correct, this sense of surprise and revelation would be a bit odd. If some brilliant star suddenly appeared shining over Bethlehem, you wouldn’t think it would take some magi showing up in Herod’s court to make them sit up and take notice of it. But this makes perfect sense if the sign were astrological. Visually, the sky in April of 6 BC was totally unremarkable. In fact, most of the planets were barely visible because they were so close to the Sun. It was only astrologers who found this configuration impressive. But because Judaism has always been wary of astrology, it’s no surprise that no one in Herod’s court or all of Jerusalem noticed the portent of this astrological omen.

So Molnar’s explanation for the Star of Bethlehem has a lot of things going for it. It seems to be able to explain why the magi say they saw the star rise in the east and then travelled to Judea, why King Herod and all of Jerusalem were unaware of the star, or at least its meaning, and then why the magi saw it again as they traveled to Bethlehem. But the theory is not without its shortcomings. I’ve already mentioned a few issues. Some, like the fact that Matthew doesn’t use the appropriate astrological terms for a heliacal rising or retrograde motion I think can be fairly easily waved away. But others are more serious. Aries was associated with all of Syria, so why did the magi travel to Jerusalem rather than a more important city like Damascus? You could make the case that Syria was not a client kingdom like Judea was, so perhaps they went to Jerusalem because they were looking for a new king and Jerusalem was where a king was.

But probably the most serious issue with the theory, is that the magi were Persian, and the sources Molnar used for interpreting the horoscope are generally Greek. Now there is a Persian source on astrology from the 3rd century that quotes several Greek astrologers, so we do know that there was cultural communication between Greece and Persia and that Persian astrology bore some influence from Greek astrology. But the truth is we don’t have any good sources for Persian or Zoroastrian astrology in the early first century AD, which is the relevant time period. It’s not entirely unreasonable that there would be similarities between Roman and Persian astrology and that Molnar’s analysis of the horoscope of 6 BC would hold up in first century Persian astrology. But it is still a pretty big speculative leap to assume that the astrology that the magis would have used was largely similar to the astrology presented by Ptolemy.

And this points to a broader issue with the astrological explanations. Astrology lacks a specific methodology. All of the great astrologers, Ptolemy included, have mentioned this and pointed to as the reason that astrology is so difficult. In modern times, if you present a group of astrologers with the same planetary configuration, you’ll find that the horoscopes they draw are only very weakly correlated with each other. If astrologers can’t agree with each other about how to interpret a horoscope, how can we expect to reverse engineer the interpretation of an astrological omen by first century Persian astrologers? Now, to be fair to Molnar’s theory, modern astrology is not systematized to the same extent that ancient astrology was. In the ancient world, astrology was an elite endeavor and required a great deal of education. If you’re trying to teach your society’s best and brightest how to read horoscopes, you need some kind of system. But today there is no system. You can’t go to school to study astrology, and anyone can put up their shingle and start reading horoscopes, so we might not be too surprised that modern astrologers agree with each other very little. But presumably ancient astrologers, working together in an imperial court, would have devised a more consistent system, if for no other reason than it would be embarrassing if they were contradicting each other at every turn. But fundamentally, the big issue is that we don’t know what that system was for the magi.

Well, I think it’s worth adding one last point to this discussion. Oftentimes in discussions about the Star of Bethlehem there is a tendency to view things in binaries — either everything happened exactly as was described in the Gospel of Matthew or the entire thing was made up. But in reality there is a spectrum of possibilities. At one end of the spectrum you could have had a series of events much like Molnar hypothesizes — there was an astrological massing when Jupiter was ascendant in Aries in April of 6 BC and this motivated a group of Persian astrologers to travel to Judea to investigate. At the other end of the spectrum the story was made up as a bit of supernatural garnish. But as an intermediate case, it’s possible that local astrologers noticed the unusual massing of 6 BC and long after the fact, in the decades after Jesus’s death, the early Christians became aware of this omen and it was incorporated into the Gospel of Matthew, but the framing of the story of magi travelling from the east was an embellishment. Or, perhaps the magi did exist, and travelled to Jerusalem and Bethlehem, but because Jesus didn’t linger in Bethlehem too long, they never actually encountered Him, and the part about them adoring the infant and presenting Him with gold, frankincense, and myrrh was the embellishment. As with so many other stories from ancient history, without some other records turning up, it is hard to make any concrete conclusions. But at a minimum, in my estimation Molnar’s theory at least provides a plausible alternative to the null hypothesis that the Star of Bethlehem was a pious fable invented by the author of the Gospel of Matthew. Some elements may have been added to the story, but the details of the magi travelling in the opposite direction from the star are unusual enough that for my money it doesn’t seem to have been entirely fabricated.

But, last month I promised you a short episode and here we are yet again, somewhere past the hour mark, so I should probably wrap it up now. So with that I hope you had a happy new year. In the next episode we’ll get back to the main thread and I’ll talk a little more about astronomy in the Roman Empire and towards the end of antiquity. I hope you’ll join me then. Until the next full moon, good night and clear skies.

Additional references

• Barthel & van Kooten, The Star of Bethlehem and the Magi