Ep. 120: The Christmas Star

Adoration of the Magi

Adoration of the Magi

With Christmas just around the corner, we thought we’d investigate a mystery that has puzzled historians for hundreds of years. In the bible, the birth of Jesus was announced by a bright star in the sky that led the three wise men to his birthplace. What are some possible astronomical objects that might look like such a bright star in the sky? And were there any unusual events that happened at that time?

  • Ep. 120: The Christmas Star
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    Fraser Cane: It’s very cold here on the west coast which is kind of normal for us in December. Usually it’s about more than freezing but we’ve had like really cold temperatures. My car got so cold it wouldn’t start.

    Dr. Pamela Gay: But from what I understand you’re working to recreate the whole White Christmas song.

    Fraser: Oh, exactly, a foot of snow everywhere and the kids have been playing out in the snow. It’s great. One other thing I thought you’d enjoy is that my 7 year-old daughter Chloe has become quite a big fan of AstronomyCast and has me play it for her every night before bed.

    She uses it to put herself to sleep actually. Anyway, but she loves it and actually now is like quite enthusiastically talking to her friends about space and astronomy. Thank you Pamela, for giving my daughter an astronomy education.

    Pamela: Well Chloe thanks a lot for listening and I hope that I don’t always put you to sleep. [Laughter]

    Fraser: We’re going to take a step away from our facts-based journey and go with a mystery that has puzzled historians for hundreds of years. In the Bible the birth of Jesus was announced by a bright star in the sky that led the three wise men to his birthplace.

    What are some possible astronomical objects that might look like such a bright star in the sky? Were there any unusual events that happened at that time? This is sort of a bit of an introduction.

    I’m actually planning on doing a show about a topic called archaeoastronomy which is where we sort of look back at what ancient astronomers knew about the night sky and the methods and tools they used to track objects and to predict eclipses and so on. And in many cases what some of those events that happened in the past can be used to sort of verify other historical events.

    It’s quite a fascinating subject and we’re going to do a whole show on that, but this is a bit of a preview. We’re going to look at one mystery in particular that a lot of people are familiar with. So Pamela, for those of us like me with absolutely no religious upbringing whatsoever, could you kind of explain the story of the Christmas star? I kind of know, I’ve seen the books and the pictures [Laughter] and I know some of the songs from school, but what is the story?

    Pamela: We’re going to try and restrict ourselves to what did the words say? We’re looking at the only Christmas Star evidence we have comes from the book of Matthew, chapter 2. It says starting right off the bat: “Now when Jesus was born in Bethlehem of Judea in the days of Herod the king, behold there came wise men from the east to Jerusalem, saying where is he that is born King of the Jews for we have seen his star in the east and are coming to worship him. When Herod the King had heard these things he was troubled and all Jerusalem with him. And when he had gathered all the chief priests and scribes of the people together, he demanded of them where Christ should be born. And they said unto him: In Bethlehem of Judea for thus it is written by the prophet. And thou Bethlehem in the land of Juda art not the least among the princes of Juda, for out of thee shall come Governor that shall rule my people Israel. Then Herod, when he had privily called the wise men, enquired of them diligently what time the star appeared. And he sent them to Bethlehem, and said: Go and search diligently for the young child; and when ye have found him, bring me word again so that I may come and worship him also. When they had heard the king, they departed and lo, the star which they saw in the east went before them till it came and stood over where the young child was.”

    Now I’d like to pull out some specific things out of that.

    Fraser: I was just going to say that, let’s sort of pull out the pieces of the puzzle then.

    Pamela: We start off with: we have three men coming from the east.

    Fraser: Now they see their Magi, who were the Magi?

    Pamela: These were basically astrologers, wise men. If we were looking in Native American culture you might think of them as the medicine men. These were people who would have been studying the sky.

    Fraser: Now they say from the east are we talking about Persia or China?

    Pamela: I’m pretty sure that it would have been one of the more Persian nations.

    Fraser: Right, okay and so they saw a star and this is the part that I don’t get. They see a star in the east but they’re coming from the east, right? So they would have seen the star in the west if it was pointing them in the right direction.

    Pamela: Yeah, so we already know that there is something with the facts-finding that we have to figure out how to sort out. How do you get Magi from the west to travel east? They’re now in Herod’s court and they see an object in the east and then follow it and it appears to then linger over Bethlehem.

    Now, the other thing in here is the reason that they’re directed to Bethlehem is because of a prophet, not because they went out and looked up at the star. So there’s this fascinating play-off going where you have the Magi coming and going, show us the king and Herod going what are you talking about? And he is calling all of his wise men in to say “what are they talking about?”

    So whatever it was that caused the Magi to travel potentially hundreds of miles wasn’t something that’s Herod’s court had even noticed. We’re looking for something that Jewish culture just didn’t notice. They weren’t dumb. They just weren’t astrologers in the same sense as the Persians.

    They looked up, they looked at the stars, they used a lunar calendar but they didn’t have the same astrological symbolism associated with whatever was going on in the sky. This might be a hint toward the answer.

    Fraser: Another key here is that Herod is alive and he was a real guy, right? He was the king of Israel. When did he die?

    Pamela: Well according to looking at coins and looking at records from other societies, we’re pretty sure he died right around 4 B.C. In general it is assumed that Jesus Christ would have been born in 4 B.C. or earlier.

    Fraser: Okay so we’ve got here people coming from the east, perhaps through some kind of prophecy and then standing in Jerusalem saw a star that was meaningful to them in the east from Jerusalem.

    Herod is alive and on the scene but for some reason Herod and his court of astrologers or astronomers didn’t see or recognize the significance of a bright object in the sky and was surprised I guess when it was pointed out to them.

    Pamela: Right and we’ve only got one record of this and it was written 50 to 70 years after it occurred.

    Fraser: What then would be some candidate objects?

    Pamela: The first place most people go is comets. There are a couple of different problems with this. There were comets along the right time-lines. There were comets recorded in both 5 B.C. and 4 B.C. by the Chinese who were amazing record-keepers and very good at keeping track of dates of things.

    We’ve been able to cross-correlate enough of the records against archaeological things in other parts of the world that we know that they were right when they made these observations.

    Fraser: So comet, now I’ve seen some comets. I saw Hale-Bopp and Hyakutake I guess about ten years ago. I’m not going to say that they looked like a star, that’s for sure. [Laughter]

    It was like a bright ball but a fairly diffuse ball and then the tail sort of way up above it – quite a long tail. It was quite spectacular, an amazing sight, right?

    Pamela: We’re kind of sorta rescued on the tail part at least because in 4 B.C. according to the Chinese records the comet actually didn’t have a tail. It’s just your happy normal comet fuzzy blob.

    Nonetheless, we have a couple of problems. If the time scale is right we have a comet without a tail, so maybe kind of a weird star. But, comets don’t really appear to hover so much. They were considered harbingers of death, doom and destruction and not kings that will rescue you.

    But there is this cultural disconnect of how do you take an object that is typically considered a harbinger of doom and have it cause you to get up, move hundreds of miles and go searching for a king?

    The other problem with these comets is Herod’s court would have noticed them. How is it that whatever it was caused Herod to ask when did this start? He has to ask the Magi because his court can’t answer that question.

    Fraser: It would have been the talk of the town that there was a bright comet in the sky. Everybody would have known about it, especially with the lack of light pollution back then.

    Pamela: Right. It’s easy to notice a faint comet only when you know where it is. So if there is this really amazing giant gorgeous comet everyone would know about it. While that type of giant gorgeous amazing comet might cause people to get up and go a few hundred miles by foot, camel and otherwise uncomfortable travel method, a kind of faint not very exciting comet that would be something an astronomer would notice.

    But not necessarily something Herod’s court would notice because they may not have been map keepers of things like comets. It’s probably not going to cause you to move hundreds of miles across the desert to go looking for a king.

    Fraser: Everyone would have known about it. It wouldn’t have come as any kind of surprise to anybody. Everyone would have known about it. Oh, yeah the comet, of course how could we not have known about a comet? Then plan B, what’s next?

    Pamela: The next thing that you see, especially in a lot of TV specials that take this on – and this is the time of year you start seeing these Christmas specials – is well maybe there was a supernova, a hyper nova, or a giant star that matches what every nativity scene has, something giant in the sky.

    Well, the problem with giant glorious wonderful supernova is why did King Herod’s court not notice it? We know that there was a supernova in 5 B.C. and it lasted for about 70 days while it was bright enough to be seen by eye.

    Fraser: How bright?

    Pamela: We don’t exactly have those records. So, you know something’s up. You know something’s new but the Chinese didn’t exactly use the modern magnitude system. The fact that it was visible for 70 days implies that it was probably about the brightest thing if not the brightest thing in the sky when it was at its brightest.

    We can see supernova on their way up and we can see them on their way down. You can imagine moving that light curve where often a supernova will only be visible by eye for maybe a couple of days on average. Take that entire light curve and take the part that’s normally only visible to the backyard astronomer and move it into the visible to the naked eye range. You suddenly get that bright point moving to the point where it is hanging out in brightness with Venus, Sirius.

    So, all of a sudden you have this bright star appearing in the sky that wasn’t there before. It’s a death star – that’s where the word nova (new) star comes in and it was hanging out for 70 days which would give the Magi time to do their traveling, talk to the king and go try and find in Bethlehem the baby Jesus.

    It seems like a pretty good candidate but these are people who like you said before live someplace without a lot of light pollution. They’re going to be aware of the constellations just like we’re aware of the brightest constellations.

    If a giant really bright star suddenly appeared in Orion, suddenly appeared in Cassiopeia, suddenly appeared in the Big Dipper, we’d notice the change in the pattern. Even the peasants would be out at the watering pond going: “Hey, Jebediah, did you see that object last night?”

    But we don’t see that. Herod’s court didn’t know about this new object. So if it was this amazingly bright absolutely fantastic supernova, why didn’t they notice it?

    Fraser: Do we know where the supernova was seen, like what constellation in the sky?

    Pamela: I haven’t been able to find those records. A lot of these things are tied into journals that you get people discussing translations and the consolation that it may be in the original Chinese records.

    But as near as I can find from my own search, I can’t find what constellation it was listed in. It would be something that would have been visible in that part of the world because we are talking the northern hemisphere in both cases.

    Fraser: I guess maybe you would want it to be something that was on the Zodiac, right? It would be something that would maybe sort of rise up and be visible on the horizon at some point in the early evening?

    Pamela: This is where you have to wonder when they say in the east how much – lots of things are in the east. Living here in St. Louis, I can refer equally to Florida being in the east and to Nova Scotia being in the east. Both of them are east of me.

    So saying that something is east doesn’t necessarily mean due east. I’m willing to give them a little bit of latitude with that. East also depends on time of day because no matter what you’re looking at in the sky, it’s going to move. It’s going to rise at a given time and it’s going to set at a given time.

    Here when you look at the passage that says: “When they had heard the king they departed and lo the star which they saw in the east went before them till it came and stood over where the young child was.”

    That actually reads very much like an astrologer, not an astronomer. But an astrologer scribing retrograde motion where they say something appears in the east moves forward continuing to progress eastward along the sky moving past stars as it goes further and further east then it came and stood over.

    As an object is about to go to retrograde motion, it appears to pause in its passage against the background stars.

    Fraser: Okay so let’s have another candidate then. What about just like a really bright star that we know of like Sirius?

    Pamela: Well, here you have to go with the – they’re not dumb based assumption. These are people that have likely achieved the highest levels of education in terms of what’s in the sky among their people. These are perhaps the people who help determine when the harvest is. They help determine when the high holidays are. They help determine the solstice and equinox dates.

    Bright stars come on an orderly basis once a year. We know when they’re coming and we know when they’re going.

    So, saying that it was just a bright star, well the bright star is always going to be there and there isn’t a king born every single year. If you start with the base assumption of they’re not dumb, just a regular everyday star just doesn’t cut it with the story.

    Fraser: If these guys were astrologers they would know Sirius like the back of their hand and wouldn’t think of any significance about it being in the sky.

    Pamela: Yeah, and the whole long journey through the desert thing, that’s a pretty good potential barrier to get over. It needs to be something unusual that had meaning to them that would cause them to move to Jerusalem.

    Fraser: Okay so we’re going to throw that one out for now. [Laughter] What other possible candidates have we got?

    Pamela: The next thing that astronomers started doing was well we have planetarium software, let’s go back and figure out where the planets were. Did the planets do anything interesting? Did they move past any particular stars? What constellations were they moving through? And more importantly, did they move close to one another?

    It was actually Kepler who first got in on the act. He goofed some of the details in the process. Kepler noticed that a bunch of the stars appeared to come close together and he said “Nova, this will cause a nova!” He was wrong. Having many planets appear together in the sky does not cause anything insane like nova to occur.

    In more modern times, we’ve had lots of people going through and looking at what are the different patterns the different planets form on the sky. In looking particularly at what planets come together it was found that in 3 B.C. on June 12th Venus and Saturn came fairly close together.

    We had then Venus and Jupiter coming very close together on August 12th. Jupiter in particular was moving through the constellation Leo and during this period of time. Jupiter actually traced a really interesting path on the sky where starting in September, 3 B.C., and continuing on for basically the next year, Jupiter appeared to pass by the star regulus which is associated with king Leonus itself.

    Then it went into retrograde motion, reversed itself and passed back out again. So, it moves forward into Leo, passes regulus, pauses and then moves backwards and then moves forward. So you have the planet that is associated with kings is all but circling the star associated with kings and doing it in a constellation that is associated with the Jews.

    It’s doing this while passing very close to Saturn and while passing very close to Venus. In particular when Venus and Jupiter were in the constellation Leo, they got so close together that they appeared as a single object. So you have two of the brightest of the planets

    Fraser: Wow.

    Pamela: essentially doing the “I’m going to look like the Nativity Star, close together, be very bright.” Now this does occur in the summer but the one piece of information we don’t really have is what time of year was Jesus born?

    The closest we can get is passages that say the shepherds were then with their sheep in the fields and it gets cold in the winter.

    Fraser: Yeah, I’ve been in Jerusalem in the winter and it’s not warm. There was snow.

    Pamela: Right, so it almost makes more sense if this story would have happened during more temperate times of the year.

    Having this conjunction, this fairly rare alignment of the planets happen during the summer actually makes sense even in the context of the shepherds and the sheep.

    Fraser: Okay, so when exactly does this conjunction happen?

    Pamela: This is where we start running into problems. This is happening in 3 B.C. and 2 B.C. which is more recent than 4 B.C. because B.C. numbers have the problem of running backwards.

    Fraser: So it’s 2 and 3 B.C. so it was like, what did you say, it was August 12th?

    Pamela: Yeah.

    Fraser: In 3 B.C. Now we’ve made a mention before, get stellarium software. It’s a free planetarium software. It lets you define your position on the globe and lets you sort of define your time. You can just play the motion of the objects in the sky backwards and forwards. So, take a look and you can kind of see how close the planets were at those times.

    I’m sure it would be amazing. I mean when you see Venus at its brightest, it’s astonishing. When you see Jupiter it is bright on its own. I just can’t imagine how bright the two would look really close together.

    But that would only be for like a day, right? You’d look at them, they’re close together and then a day later they’re starting to get far apart again.

    Pamela: Right and you can actually just watch them come together and pass apart. As this is happening you have Venus at about minus 4-magnitude, Jupiter at basically minus 2-magnitude.

    That’s the type of event that as you see these planets getting closer and closer together in the sky and then essentially passing on top of each other you can almost imagine Magi getting up and going: “Ooh, Leo. That’s the constellation that rules the Jews. We have Jupiter that rules kings. Let’s get up and go to Jerusalem and find out what’s on. This is cool.”

    Fraser: Are there any problems with this scenario?

    Pamela: Yeah, Herod’s dead.

    Fraser: Herod’s dead! [Laughter] So on the date when this conjunction happens Herod has already died.

    Pamela: Right, so either we don’t quite know when Herod was alive; we think we do because it’s kind of stamped on coins.

    Fraser: Right, that one is pretty certain.

    Pamela: Either the whole time scale is screwed up, we lost two or three years in the past 2,000 or we have the wrong king. Again, Matthew was written 50 to 70 years after Jesus died.

    Fraser: He just like had the wrong guy? He thought he was talking Herod but actually it was, I don’t know.

    Pamela: Yeah. So we’ve just got the wrong king. So here we only have one version of this particular story, or we have to eliminate our other facts-based possibility to answering this mystery. Here’s where we end up face-to-face with what all archaeoastronomers are faced with.

    We’re assuming we understand the culture of the Magi. We don’t have a lot of information to go on. We are assuming that when they say Herod’s priests and scribes hadn’t noticed what was going on in the sky that that’s true and not just Herod hadn’t noticed what was going on in the sky and the priests and Magi played dumb because they didn’t want to say that the knew something their king hadn’t noticed.

    Something somewhere doesn’t match and we can’t go back and stand in Herod’s court and go: “Yes you are actually Herod. Scribes you’re dumb or you’re lying. Magi, we got your culture wrong. It was actually a comet in a constellation that made no sense.”

    Somewhere in here there may be truth but all we have is the facts and the facts we have is there was a pretty bright supernova. The facts we have is there were comets in the right period of time. The facts we have is there was this really neat dance of the planets.

    It would just be so cool to see first Jupiter and Saturn being close together; to see Jupiter essentially circling Regulus. And to see Jupiter and Venus coming together away from the Sun such that they’re basically touching. Now Jupiter and Venus do get together in a hundred, couple hundred year timescale, but not this close.

    Sometimes when it happens, it happens close to the Sun. Back in 2000 these two planets appeared very close together but it was right next to the Sun and we wouldn’t have been able to see it if it wasn’t for the SOHO Satellite.

    The answer that makes the most sense is we have the wrong king. The other answers that make less sense would imply that something got written down wrong. It leaves us with no satisfying answer.

    It’s a mystery and maybe some day we’ll turn up more documents and records. Maybe we’ll find some other society that can confirm or deny the facts.

    Fraser: So until then we’ll just wait for more facts.

    Pamela: That’s as far as we can go today. But archaeoastronomy is a really cool thing to try and follow. And just that we can look to Chinese records to confirm things the Mayans recorded, we can look to things Mayans recorded to try and make sense out of Native American ruins.

    We do know that people were looking at the sky and making accurate notations for thousands of years. Even though they didn’t know they were doing science, they were perhaps at least citizen scientists allowing us to know that supernova have been going off and now we can look to see what we can learn about them.

    Fraser: On that note, I hope you have a happy, Merry Christmas, Pamela.

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