0:00:03 > 0:00:07Christmas means different things to different people.
0:00:07 > 0:00:10To some of us, it's about tradition.
0:00:10 > 0:00:13For others, it's family and presents.
0:00:13 > 0:00:17And for some, it's about the religious message that underpins it all.
0:00:19 > 0:00:23But this is an astronomy show, and there's one piece of the Christmas story
0:00:23 > 0:00:27that is particularly relevant to us - the Star of Bethlehem.
0:00:27 > 0:00:30So tonight, we're going in search of the Christmas Star.
0:00:39 > 0:00:42We'll be looking for the real astronomical phenomena that
0:00:42 > 0:00:46could have caused a new star to appear 2,000 years ago.
0:00:48 > 0:00:52The candidates are some of the most exciting objects in the night sky.
0:00:59 > 0:01:01Welcome to a Sky at Night Christmas special.
0:01:37 > 0:01:40Astronomers have been speculating about the cause of
0:01:40 > 0:01:43the Star of Bethlehem for centuries.
0:01:43 > 0:01:45And there have been all sorts of suggestions as to
0:01:45 > 0:01:47what it might have been.
0:01:49 > 0:01:52And they've varied from the plausible to the ridiculous.
0:01:52 > 0:01:53Could it really have been a UFO?
0:01:53 > 0:01:55Well, probably not.
0:01:55 > 0:01:57But tonight we've whittled the list down
0:01:57 > 0:01:59to the six most plausible candidates.
0:01:59 > 0:02:02And over the course of the programme with the help of our experts,
0:02:02 > 0:02:07we'll be presenting the case for each of these six possibilities.
0:02:07 > 0:02:10In order to choose the most likely explanation, we'll be
0:02:10 > 0:02:15reconstructing the skies over Jerusalem 2,000 years ago...
0:02:16 > 0:02:19This coming together of these two planets,
0:02:19 > 0:02:21I interpret as the Star of Bethlehem.
0:02:22 > 0:02:26..and examining the case for all the prime candidates.
0:02:27 > 0:02:33And above the stable, poised majestically in the sky, is a beautiful comet.
0:02:33 > 0:02:36Dallas Campbell will be sifting through the archaeological
0:02:36 > 0:02:42and the historical evidence for events in the skies of the Middle East two millennia ago.
0:02:42 > 0:02:45This is real historical evidence
0:02:45 > 0:02:47to say at that time, there was an astronomical event that was
0:02:47 > 0:02:51important, that people wrote down, that would have looked spectacular.
0:02:51 > 0:02:54And finally, Maggie and I will assess the evidence and make
0:02:54 > 0:02:57our choice as to what we think the Star of Bethlehem might have been.
0:03:00 > 0:03:05But first, Chris introduces perhaps the most dramatic of our six candidates.
0:03:08 > 0:03:11The typical Christmas-card image of the Star of Bethlehem
0:03:11 > 0:03:15is of a bright new star that suddenly blazes to life in the sky.
0:03:19 > 0:03:22That's an event we know can happen in nature -
0:03:22 > 0:03:26because in 1604, that exact phenomenon was observed
0:03:26 > 0:03:30by Johannes Kepler, one of the greatest astronomers of them all.
0:03:32 > 0:03:35His record of the event can still be found in the library
0:03:35 > 0:03:37of the Royal Astronomical Society.
0:03:40 > 0:03:44And this wonderful book contains Kepler's writings on the subject.
0:03:44 > 0:03:46It was printed in 1606.
0:03:46 > 0:03:50It's one of only 35 copies left in the world - so I'm going to
0:03:50 > 0:03:54be very careful with it and try and turn to the title page.
0:03:54 > 0:03:59And we can see that the title is "Stella Nova In Pede Serpentarii".
0:03:59 > 0:04:04That's "The New Star in the Foot of the Serpent Bearer" - that's the constellation we call Ophiuchus.
0:04:04 > 0:04:06In fact, to confirm that we don't need the title -
0:04:06 > 0:04:11we can turn on to Kepler's own star map.
0:04:11 > 0:04:12Here it is.
0:04:12 > 0:04:14You can see the familiar constellations
0:04:14 > 0:04:17and there's Ophiuchus with his serpent wrapped
0:04:17 > 0:04:22round him, and the new star is down here in his foot, marked N for new.
0:04:22 > 0:04:26And Kepler described this star as like a torch blown by a strong wind.
0:04:26 > 0:04:30He said it was the most beautiful and glorious star ever seen.
0:04:30 > 0:04:33So he was clearly impressed with his discovery, both from
0:04:33 > 0:04:37a sort of scientific point of view, but also, remember, he was
0:04:37 > 0:04:41a devout Christian, he believed in astrology, and so a new star must
0:04:41 > 0:04:45mark something significant happening on Earth or in the heavens.
0:04:45 > 0:04:46If we flick on, we can see him
0:04:46 > 0:04:51writing to an adviser to the court of Rudolph II, to whom the book is
0:04:51 > 0:04:55dedicated, and he says, "The star that led the Magi" - the wise men -
0:04:55 > 0:04:58"to Christ's manger might have had some relation to our star."
0:04:58 > 0:05:04In other words, he thinks he's just seen the modern equivalent of the Star of Bethlehem.
0:05:04 > 0:05:08What Kepler didn't know was what had caused the new star to appear.
0:05:10 > 0:05:14Today, we know it was not caused by a star's birth,
0:05:14 > 0:05:17but by its violent death.
0:05:17 > 0:05:19A supernova.
0:05:20 > 0:05:23This is how the most common type of supernova works.
0:05:23 > 0:05:29A star is always in danger of collapsing in on itself, due to its own gravity.
0:05:29 > 0:05:34The only thing that stops this is the energy produced by fusion taking place in its core.
0:05:34 > 0:05:37This provides an outward pressure which keeps the star stable.
0:05:38 > 0:05:43When it runs out of fuel, it can no longer resist its own gravity
0:05:43 > 0:05:47and it collapses and rebounds in a massive explosion.
0:05:50 > 0:05:54It releases as much energy in that single instant as our sun
0:05:54 > 0:05:57will release in its entire lifetime.
0:05:57 > 0:06:02It suddenly becomes brighter than tens of billions of ordinary stars.
0:06:02 > 0:06:07This picture shows a supernova almost outshining an entire galaxy.
0:06:09 > 0:06:13And poetically, the explosive death of these stars are ultimately
0:06:13 > 0:06:17responsible for the creation of life, as they spread the elements
0:06:17 > 0:06:21essential for life throughout the universe.
0:06:21 > 0:06:23Supernovae aren't rare.
0:06:23 > 0:06:28In fact, it's thought that throughout the universe, ten occur every second.
0:06:28 > 0:06:31But most of these are too distant to notice
0:06:31 > 0:06:35and they can only be picked up by the most powerful telescopes.
0:06:35 > 0:06:37But sometimes, every few hundred years,
0:06:37 > 0:06:40a supernova occurs within our own galaxy.
0:06:46 > 0:06:50We know from Kepler's accounts that a nearby supernova is
0:06:50 > 0:06:52one of the most impressive sights in the sky.
0:06:53 > 0:06:56But we have not seen anything like it since 1604.
0:06:58 > 0:07:03All we can find today are the traces that supernovae leave behind.
0:07:03 > 0:07:06This is the remnant left by Kepler's Supernova.
0:07:08 > 0:07:12And this is the Crab Nebula, a cloud of gas and dust, created by another
0:07:12 > 0:07:17supernova explosion that appeared in the skies 500 years earlier.
0:07:18 > 0:07:22When the light from this explosion reached Earth 1054,
0:07:22 > 0:07:26it was as if a new star suddenly appeared in the night sky.
0:07:26 > 0:07:30It blazed as bright as the moon for two years before fading.
0:07:30 > 0:07:33But it made a huge impression on the people of the time.
0:07:33 > 0:07:36And a new star was recorded by the Chinese, the Japanese
0:07:36 > 0:07:38and also in the Middle East.
0:07:39 > 0:07:42These rock paintings in the American South West are thought to
0:07:42 > 0:07:46show the position where the supernova appeared in the sky.
0:07:47 > 0:07:53Just like Kepler's Supernova, the 1054 event had made a huge impact.
0:07:55 > 0:07:58That's why I think that a supernova is a great candidate to be
0:07:58 > 0:08:00the Star of Bethlehem.
0:08:00 > 0:08:03If a supernova had occurred 2,000 years ago, it's easy
0:08:03 > 0:08:08to see why people would have taken it as an omen of great events happening here on Earth.
0:08:23 > 0:08:26A bright supernova appearing suddenly
0:08:26 > 0:08:28does seem to fit all the facts -
0:08:28 > 0:08:32that's why it's been such a popular explanation for more than 400 years.
0:08:32 > 0:08:35But to really find out what the Star of Bethlehem was
0:08:35 > 0:08:37or whether it existed at all,
0:08:37 > 0:08:40we need to find an accurate description in the historical record.
0:08:40 > 0:08:44And so, we've sent Dallas Campbell to see what he could dig up.
0:08:49 > 0:08:53The first place to start searching for a record of the star is,
0:08:53 > 0:08:54of course, in the Bible.
0:08:56 > 0:09:00Even there, it's only mentioned in one place -
0:09:00 > 0:09:01in the Gospel of St Matthew.
0:09:03 > 0:09:08"When Jesus was born in Bethlehem of Judaea in the days of Herod
0:09:08 > 0:09:11"the King, wise men from the East came to Jerusalem,
0:09:11 > 0:09:15"saying, 'Where is he that is born King of the Jews?
0:09:15 > 0:09:21" 'For we have seen his star in the East and are come to worship him.'
0:09:21 > 0:09:23"Then Herod privily called the wise men,
0:09:23 > 0:09:27"and learned of them exactly what time the star appeared.
0:09:27 > 0:09:32"And they, having heard the King, went their way, and lo,
0:09:32 > 0:09:35"the star, which they saw in the East, went before them,
0:09:35 > 0:09:40"till it came and stood over where the young child was.
0:09:40 > 0:09:47"And when they saw the star, they rejoiced with exceeding great joy."
0:09:47 > 0:09:50And that is it. We just have those few paragraphs.
0:09:50 > 0:09:53The wise men, they see the star, which brings them to Jerusalem.
0:09:53 > 0:09:57We don't know who they are, we don't know how far they've come.
0:09:57 > 0:09:59They then see the star again,
0:09:59 > 0:10:01which leads them to nearby Bethlehem.
0:10:01 > 0:10:04As a piece of writing, it's poetic,
0:10:04 > 0:10:07but as a historical document, it doesn't give us a lot to go on.
0:10:11 > 0:10:15The Gospel According To St Matthew was written at least 70 years after
0:10:15 > 0:10:16the events it describes.
0:10:16 > 0:10:20So if I want a more reliable historical document,
0:10:20 > 0:10:22I'm going to have to look elsewhere.
0:10:22 > 0:10:25The problem is where and when to look, because of course,
0:10:25 > 0:10:28we're not entirely sure when all this happened.
0:10:30 > 0:10:32One thing we are sure of
0:10:32 > 0:10:37is that the Star of Bethlehem didn't appear on 25th December, zero AD.
0:10:37 > 0:10:40I've come to see the Reverend Robin Griffiths-Jones to see if he
0:10:40 > 0:10:45can tell me where in the historical records I should be looking.
0:10:45 > 0:10:47Let me ask you about the birth of Jesus.
0:10:47 > 0:10:53Why do we think Jesus was NOT born on 25 December, 2,015 years ago?
0:10:53 > 0:10:58This is the kind of date we have - but it's arbitrary, isn't it?
0:10:58 > 0:11:00It is slightly arbitrary. We'll do it in two stages.
0:11:00 > 0:11:02First of all, we do the time of year.
0:11:02 > 0:11:05So why do we think he was born on the 25th December?
0:11:05 > 0:11:08The Romans - the pagan Romans celebrated the end of December
0:11:08 > 0:11:11with huge festivities - the Saturnalia,
0:11:11 > 0:11:16the god Mithras, the winter solstice, everything gathered around this dark, cold time of year
0:11:16 > 0:11:19as they looked forward to the future and the next year.
0:11:19 > 0:11:23And so, it's easy. You see what happened - the Christians simply took over and Christianized this.
0:11:23 > 0:11:26And we're happy with that. Can we be more specific about a year?
0:11:26 > 0:11:29Just in terms of what we're looking for here.
0:11:29 > 0:11:31- Of course you do - you want the year. - Can we narrow it down?
0:11:31 > 0:11:36Obviously, the calendar itself that we're working with presumably post-dates that anyway.
0:11:36 > 0:11:38Of course it does, yes.
0:11:38 > 0:11:41- We've plumped for the present dating...- OK.
0:11:41 > 0:11:44..which makes this year 2015,
0:11:44 > 0:11:48based upon the calculations of an extraordinary monk called
0:11:48 > 0:11:51Dionysius Exiguus. He did an extremely complicated
0:11:51 > 0:11:55calculation of the dates of Easter for the 95 years
0:11:55 > 0:11:58leading on from his own time in AD 525.
0:11:58 > 0:12:03And while he was about this, he realised it was an opportunity
0:12:03 > 0:12:08to recalibrate the entire dating system of the world, of the then-Christian world.
0:12:08 > 0:12:13It had previously been based on the years of the Emperor Diocletian,
0:12:13 > 0:12:15a persecutor of the Christians.
0:12:15 > 0:12:20And AD had meant Anno Diocletiani - the year of Diocletian.
0:12:20 > 0:12:23Dionysus would have none of it, he was going to start with
0:12:23 > 0:12:25the year of Domini - the Lord.
0:12:25 > 0:12:29- And so, he had to calculate the year of the birth of Jesus.- Right.
0:12:29 > 0:12:37And he reckons that Jesus was born 753 years after the foundation of the city of Rome.
0:12:37 > 0:12:40Bingo! But he didn't get it right. He didn't get it right.
0:12:40 > 0:12:44We know actually a couple of mistakes he made,
0:12:44 > 0:12:46which meant he ended up about four years out.
0:12:46 > 0:12:50This is good news, because we know that Jesus was born
0:12:50 > 0:12:52while Herod the Great was still alive.
0:12:52 > 0:12:57- Herod the Great died in 4BC, almost certainly.- OK.
0:12:57 > 0:13:02We know when he died, because we're told he died after a lunar eclipse, shortly before Passover.
0:13:02 > 0:13:05And we know there was a lunar eclipse in 4BC, one month before Passover.
0:13:05 > 0:13:06- Bingo.- And that's reliable -
0:13:06 > 0:13:11- it's interesting we're looking at astronomical events to date. - We really are. Indeed, we are.
0:13:11 > 0:13:13Can I ask you about this star?
0:13:13 > 0:13:17You're not bothered it had to be on the day of his birth.
0:13:17 > 0:13:18- Oh, good heavens, no!- OK, well...
0:13:18 > 0:13:21It might have been a year before Jesus was born.
0:13:21 > 0:13:23Two years before Jesus was born.
0:13:23 > 0:13:26So if I'm going to continue my search to look for some
0:13:26 > 0:13:28kind of astronomical event,
0:13:28 > 0:13:31if Herod died in 4BC, where does that leave us?
0:13:31 > 0:13:35Well, I think we're likely to look at the two or three years before.
0:13:35 > 0:13:38- So let's make seven to four the main inquiry.- Seven to four. OK.
0:13:38 > 0:13:39Thank you very much indeed.
0:13:39 > 0:13:42- You've given me some more clues. - I hope so.- Thank you, Robin.
0:13:42 > 0:13:44Real pleasure, real pleasure.
0:13:46 > 0:13:47Well, hopefully that gives us
0:13:47 > 0:13:51a little bit of a clearer idea in terms of an actual date.
0:13:51 > 0:13:53Our next task is to find out
0:13:53 > 0:13:55what was going in the night sky at that time.
0:13:57 > 0:14:00That is, if the star existed at all!
0:14:05 > 0:14:08I kind of think there was something
0:14:08 > 0:14:13that took place in the Near East around the time that Jesus
0:14:13 > 0:14:19was born, that the writer of the Gospel of Matthew was drawing on and building up in terms
0:14:19 > 0:14:23of a meaning story - but he wasn't creating it out of nothing.
0:14:23 > 0:14:25The idea that the heavens would indicate
0:14:25 > 0:14:30something big was going to happen was seen as perfectly normal.
0:14:30 > 0:14:33You've got to bear in mind, of course, at that time,
0:14:33 > 0:14:37many, many things could not be predicted - life, death, famine,
0:14:37 > 0:14:39harvest failure, things of that sort,
0:14:39 > 0:14:43and it was very easy, after the event, that you might say,
0:14:43 > 0:14:47"Oh, yes, just before the flood came, just before the harvest failed,
0:14:47 > 0:14:51"there was a comet, there was a conjunction, there was something like that."
0:14:51 > 0:14:56So people were always looking heavenwards to try to understand not
0:14:56 > 0:14:59just how the world worked, but why it worked in the way that it did.
0:15:01 > 0:15:05History suggests that we should be looking for an event that
0:15:05 > 0:15:07happened in the sky between 7 and 4BC.
0:15:09 > 0:15:13But what sort of astronomical event would have attracted
0:15:13 > 0:15:17the attention of the wise men, or the Magi, as they were known?
0:15:17 > 0:15:23Some of the possibilities, like supernovae, would have been very dramatic.
0:15:23 > 0:15:27But Chris has been investigating a more subtle possibility.
0:15:27 > 0:15:30Not all the candidates to be the Star of Bethlehem are stars.
0:15:30 > 0:15:34Some believe that the thing that set the Magi on their journey was
0:15:34 > 0:15:35an alignment of planets.
0:15:35 > 0:15:39So I've come here to the Royal Observatory, Greenwich,
0:15:39 > 0:15:42with its Peter Harrison planetarium, to simulate the night sky
0:15:42 > 0:15:44at the time of Jesus' birth.
0:15:59 > 0:16:02Astronomer David Hughes has been studying
0:16:02 > 0:16:06the Star of Bethlehem for over 30 years and he thinks he's located it
0:16:06 > 0:16:11in an event that occurred in the skies above the Middle East in 7BC.
0:16:14 > 0:16:18Well, David, we've got the night sky as seen from Jerusalem a little
0:16:18 > 0:16:19more than 2,000 years ago
0:16:19 > 0:16:21and it looks pretty familiar to me.
0:16:21 > 0:16:23Well, it is familiar.
0:16:23 > 0:16:25The constellation shapes have hardly changed.
0:16:25 > 0:16:29And we have these two wonderful planets, Jupiter and Saturn,
0:16:29 > 0:16:34and they're close together and of course, astrologically,
0:16:34 > 0:16:37the fact that they're close together means you've got a conjunction.
0:16:37 > 0:16:42They came together in the year 7BC
0:16:42 > 0:16:46and this coming together of these two planets,
0:16:46 > 0:16:48I interpret as the Star of Bethlehem.
0:16:48 > 0:16:50We can watch that using the planetarium.
0:16:50 > 0:16:53So this is the 27th March, 7BC,
0:16:53 > 0:16:57and if we run time forwards, you can tell us what happens.
0:16:57 > 0:17:00What we're seeing is they're coming together.
0:17:00 > 0:17:02They don't merge, they come together.
0:17:02 > 0:17:04- They get pretty close. - They get pretty close.
0:17:04 > 0:17:08But this is not just one conjunction.
0:17:08 > 0:17:11Over the course of several months,
0:17:11 > 0:17:14the two planets came together three times -
0:17:14 > 0:17:16a so-called triple conjunction.
0:17:17 > 0:17:22So these two planets were seen close together first in the dawn sky -
0:17:22 > 0:17:26what is known in Matthew as "in the East" - and of course
0:17:26 > 0:17:29then, as the months passed,
0:17:29 > 0:17:33you got them appearing close together in the evening sky.
0:17:33 > 0:17:39And I think, personally, the Magi thought that this indicated the actual birth date
0:17:39 > 0:17:42of this new King of the Jews.
0:17:42 > 0:17:44OK - so when was that date?
0:17:44 > 0:17:47That date was Tuesday 23rd September.
0:17:47 > 0:17:49OK, so Christmas was three months ago,
0:17:49 > 0:17:51so that's good, we've got that out of the way!
0:17:52 > 0:17:56This interpretation of the Star of Bethlehem requires that the Magi
0:17:56 > 0:18:01had a detailed understanding of the movement of the planets in the sky.
0:18:01 > 0:18:04They must have been skilled astronomers.
0:18:04 > 0:18:09But it also requires that they gave very specific astrological meaning
0:18:09 > 0:18:12to this interaction between Jupiter and Saturn.
0:18:12 > 0:18:16But conjunctions happen reasonably often - triple conjunctions less so.
0:18:16 > 0:18:19But why do you think THIS was the Star of Bethlehem?
0:18:19 > 0:18:22Firstly, as you say, conjunctions do happen all the time.
0:18:22 > 0:18:25Triple conjunctions don't.
0:18:25 > 0:18:29You've got to get, in essence, sun, Earth and the two objects lined up
0:18:29 > 0:18:32for a triple conjunction, so that's rarer.
0:18:32 > 0:18:38And then, the next thing is you've got to introduce actually where in the sky this is happening.
0:18:38 > 0:18:40And that is in the constellation of Pisces.
0:18:40 > 0:18:42And we can call that up - this is the magic of the Planetarium.
0:18:42 > 0:18:45- There you see Pisces and this is rare.- Yes.
0:18:45 > 0:18:48It takes place round about every 800-900 years.
0:18:48 > 0:18:49And so the Magi would say,
0:18:49 > 0:18:53"Ah! That means this new ruler is in Israel."
0:18:55 > 0:18:57Hang on - how do you go from Pisces to Israel?
0:18:57 > 0:19:00Well, I don't, but the astrologers 2,000 years ago
0:19:00 > 0:19:04actually divided the zodiac up into 12 different constellations,
0:19:04 > 0:19:07and each of these constellations was associated with
0:19:07 > 0:19:11- one of their neighbouring countries. - Oh, OK - there's a list somewhere?
0:19:11 > 0:19:14- Yes. in Ptolemaic astrology, there is a list.- OK.
0:19:14 > 0:19:18Pisces - Israel. Aries - Syria. And so on.
0:19:18 > 0:19:23The Magi, of course, would have been spending their lives looking at the planets.
0:19:23 > 0:19:25They knew what was going to happen - a new king,
0:19:25 > 0:19:30they know where it was going to happen - Pisces indicating the vicinity of Jerusalem,
0:19:30 > 0:19:33and they knew when it was going to happen.
0:19:33 > 0:19:37It strikes me that this is the opposite of the primary-school version of the story,
0:19:37 > 0:19:41where we have the big, shiny star that hovers in front of the wise men
0:19:41 > 0:19:42and settles over the stable.
0:19:42 > 0:19:46This is a scientific story you're telling - calculations,
0:19:46 > 0:19:49observations that test them and then a conclusion.
0:19:49 > 0:19:51There's no big, shiny star.
0:19:51 > 0:19:55But if you read Matthew carefully, there's nothing indicating
0:19:55 > 0:19:58that the star was out of ordinary.
0:19:58 > 0:20:03And it is of course important that you have a star that Herod hadn't noticed.
0:20:03 > 0:20:04He hadn't noticed when it had started -
0:20:04 > 0:20:08he wanted to know exactly when Jesus was born.
0:20:08 > 0:20:11So you want something that is a bit subtle.
0:20:11 > 0:20:19And this 7BC triple conjunction does fit in with the general history of the times.
0:20:19 > 0:20:22Well, whatever the truth of it is, I really like the idea that there were these people
0:20:22 > 0:20:26back then looking up and enjoying the sky just as we do today.
0:20:26 > 0:20:29- David, thank you very much. - Pleasure.
0:20:29 > 0:20:31So that's two candidates down.
0:20:32 > 0:20:34The bright new star of the supernova
0:20:34 > 0:20:37that surely everyone would have noticed.
0:20:38 > 0:20:42And the much subtler planetary conjunction, which could explain
0:20:42 > 0:20:45why it was only seen by the wise men.
0:20:46 > 0:20:49But who were the Magi and where did they come from?
0:20:52 > 0:20:56Some scholars think the Magi are Mesopotamian.
0:20:56 > 0:21:00Mesopotamia, in particular Babylon, had a great reputation for astronomy
0:21:00 > 0:21:05and astrology, so there was a sense in which if men were going to come from the East,
0:21:05 > 0:21:07they were likely to be from Mesopotamia.
0:21:07 > 0:21:09What would today be Iraq.
0:21:09 > 0:21:13A part of the world, of course, in those days with a very rich culture,
0:21:13 > 0:21:17Babylon, Nineveh, Sipur and so on.
0:21:17 > 0:21:21They would have been men who had been taught how to read the heavens.
0:21:26 > 0:21:31So if the Magi were from Mesopotamia, what more can we find out about them?
0:21:31 > 0:21:35Their culture is long gone and the ancient cities of Babylon have been
0:21:35 > 0:21:39abandoned for thousands of years, but we do have some clues.
0:21:39 > 0:21:42There were definitely skilled Babylonian astronomers who
0:21:42 > 0:21:45left behind crucial historical records which may shed light
0:21:45 > 0:21:49on the triple conjunction theory.
0:21:49 > 0:21:52Today they can be found in the British Museum
0:21:52 > 0:21:55under the watchful gaze of Christopher Walker.
0:21:55 > 0:21:59Christopher - can you just tell us what these wonderful objects are?
0:21:59 > 0:22:02What you see now are tablets that actually we have
0:22:02 > 0:22:04baked for the sake of their conservation -
0:22:04 > 0:22:07but in antiquity, they would have had wet clay, they would have
0:22:07 > 0:22:11flattened it out to make an oblong shape like that and then they would
0:22:11 > 0:22:14have taken their stylus and written their cuneiform wedges.
0:22:14 > 0:22:17I see, I didn't... So the fact that they're baked -
0:22:17 > 0:22:20it was us who did this, I didn't realise that. That's amazing.
0:22:20 > 0:22:24And let me ask about the people who would have written on these tablets.
0:22:24 > 0:22:27Who were they and how accurate would they have been
0:22:27 > 0:22:29and why were they making these records?
0:22:29 > 0:22:34These were written by professional Babylonian scribes, who were hired
0:22:34 > 0:22:39by the temple, basically for life, to sit there making astronomical
0:22:39 > 0:22:43observations, watching everything that happened in the sky, day and
0:22:43 > 0:22:47night and then do the mathematical calculations month by month,
0:22:47 > 0:22:53year by year, to predict various astronomical events in the sky
0:22:53 > 0:22:57- and tell you to what kind of things on Earth it might relate...- OK.
0:22:57 > 0:23:01..whether it is relating to the king or the crops, or the like.
0:23:01 > 0:23:02So written in Babylonian.
0:23:02 > 0:23:05Can you show me here
0:23:05 > 0:23:08which of these symbols are actually representing the planets
0:23:08 > 0:23:11and where they are, where they would be in the sky?
0:23:11 > 0:23:17In this line here, it says that Jupiter and Saturn were in Pisces.
0:23:17 > 0:23:20Gosh, so this is the idea of conjunctions.
0:23:20 > 0:23:22This is exactly the idea of conjunctions - this is
0:23:22 > 0:23:25actually the single line that expresses that best
0:23:25 > 0:23:29and it will then go on to tell you a little bit about the moon and the sun
0:23:29 > 0:23:33and the points at which the moon changes its position,
0:23:33 > 0:23:35or they have an eclipse or the like.
0:23:35 > 0:23:37What year would this one be from?
0:23:37 > 0:23:42These three tablets all date to the year 7-6BC.
0:23:42 > 0:23:45- Which is exactly the time we're looking for.- Exactly.
0:23:45 > 0:23:48So that...so right there - that's it.
0:23:48 > 0:23:52That is the famed triple conjunction that could be,
0:23:52 > 0:23:55- may be our candidate.- Yes, yes.
0:23:55 > 0:23:58So this is real historical evidence to say at that time,
0:23:58 > 0:24:00there was an astronomical event that was important,
0:24:00 > 0:24:03that people wrote down, that would have perhaps looked spectacular.
0:24:03 > 0:24:07It shows us that there were a group of astronomers working at Babylon
0:24:07 > 0:24:10who would have been able to predict the event
0:24:10 > 0:24:13and understand its significance, whatever that may have been to them.
0:24:13 > 0:24:17I mean, what do you think? Do you think that could be a contender?
0:24:17 > 0:24:19It's at least a possible contender.
0:24:19 > 0:24:23- It's the only one at least for which we have a written record.- Yeah.
0:24:23 > 0:24:26The problem is both is that it's not quite as spectacular
0:24:26 > 0:24:29a conjunction as you might hope, and secondly,
0:24:29 > 0:24:33we have hardly any idea what they would have made of a conjunction.
0:24:33 > 0:24:38- Yeah.- Absolutely none of our astronomical texts mentions the West in anything
0:24:38 > 0:24:40other than the vaguest terms.
0:24:40 > 0:24:43The same to some extent would apply to the Magi.
0:24:43 > 0:24:47We have no idea that seeing this kind of planetary conjunction would have
0:24:47 > 0:24:50sent them running off to see King Herod in Jerusalem.
0:24:50 > 0:24:54There seem to be more questions than answers, really.
0:24:54 > 0:24:57I'm going to continue on my journey. I'm going to continue
0:24:57 > 0:24:59and look at the other options, but this is fascinating.
0:24:59 > 0:25:02It's really interesting to actually see something physical as well.
0:25:02 > 0:25:05- Something concrete, as it were, written down. Thank you.- OK.
0:25:07 > 0:25:12So we've got good reliable historical evidence that there was this planetary conjunction,
0:25:12 > 0:25:16and people were seeing it, observing it and writing it down.
0:25:16 > 0:25:20Whether they then attributed any significance to it is another story.
0:25:20 > 0:25:23So I'm going to keep on searching to see what else is out there.
0:25:24 > 0:25:29But while we may be able to find archaeological evidence of the star,
0:25:29 > 0:25:33is there any chance we can find a trace of it in the sky today?
0:25:33 > 0:25:36Pete Lawrence has been out stargazing,
0:25:36 > 0:25:40looking for examples of our two candidates so far.
0:25:40 > 0:25:44But he also has some new possibilities to suggest.
0:25:44 > 0:25:47Now, our first candidate are planetary conjunctions.
0:25:47 > 0:25:50These aren't that uncommon, so we can see the same
0:25:50 > 0:25:54sort of events today that ancient astronomers would have seen.
0:25:54 > 0:25:57At the moment, we've got brilliant Jupiter and Venus
0:25:57 > 0:26:01shining away spectacularly, just above the clouds there.
0:26:01 > 0:26:03Now, at the moment, they look quite well separated,
0:26:03 > 0:26:07but just a few weeks ago, they were really close together,
0:26:07 > 0:26:10and that was enough of a draw to get people up early in the morning
0:26:10 > 0:26:13and take some spectacular photographs of them.
0:26:15 > 0:26:18The conjunction was especially striking when Venus
0:26:18 > 0:26:22and Jupiter were also joined in the morning sky by Mars.
0:26:22 > 0:26:25You can see why something similar would have appealed to
0:26:25 > 0:26:27ancient astronomers in 7BC.
0:26:30 > 0:26:34But it's not just planetary conjunctions that we can see today.
0:26:34 > 0:26:39We can also find evidence of some of the other candidates thought to be the Star of Bethlehem.
0:26:39 > 0:26:43Unless we're unbelievably lucky in the next few hours,
0:26:43 > 0:26:46we're probably not going to see a naked eye supernova this evening.
0:26:46 > 0:26:49But there are plenty of stars which have the possibility of going
0:26:49 > 0:26:52supernova relatively soon.
0:26:52 > 0:26:55And one such candidate is Betelgeuse
0:26:55 > 0:26:59in the famous constellation of Orion, the Hunter.
0:27:00 > 0:27:03If you look at the constellation of Orion,
0:27:03 > 0:27:06Betelgeuse is at its left-hand shoulder
0:27:06 > 0:27:08and it is a distinct red colour.
0:27:08 > 0:27:10That's because as it reaches the end of its life,
0:27:10 > 0:27:13it has swollen up to become a red giant.
0:27:15 > 0:27:19Betelgeuse is now over a billion miles across.
0:27:19 > 0:27:21If you put it at the heart of our solar system, it would
0:27:21 > 0:27:25engulf the inner planets and extend out almost as far as Saturn.
0:27:28 > 0:27:30Sometime soon, and that can mean
0:27:30 > 0:27:32anywhere in the next few million years,
0:27:32 > 0:27:34it'll go off as a supernova.
0:27:34 > 0:27:39And because it's relatively close to us, at 646 light years' distance,
0:27:39 > 0:27:42it's going to put on one hell of a show in the night sky.
0:27:43 > 0:27:46Betelgeuse is ten times closer than the star
0:27:46 > 0:27:48that gave rise to the Crab Nebula,
0:27:48 > 0:27:52or around 30 times closer than the supernova that Kepler saw.
0:27:54 > 0:27:57So when it does go, it will be much brighter -
0:27:57 > 0:28:01brighter even the moon and probably visible in broad daylight.
0:28:01 > 0:28:05Perhaps the Star of Bethlehem was something like this.
0:28:05 > 0:28:08If you didn't know what caused it, I can see how that would easily
0:28:08 > 0:28:12be mistaken for some sort of divine message.
0:28:12 > 0:28:15But there are other suggestions of what the star might have
0:28:15 > 0:28:17been that we can see today.
0:28:18 > 0:28:21Some have suggested it might have been an aurora -
0:28:21 > 0:28:23seen much further south than usual.
0:28:23 > 0:28:24Rare but not unknown.
0:28:25 > 0:28:28Or it could have been the zodiacal light -
0:28:28 > 0:28:32a faint glowing pillar that appears above the horizon caused by light
0:28:32 > 0:28:37scattering through dust that fills the plane of the solar system.
0:28:37 > 0:28:40But there is one other suggestion which I want to tell you about -
0:28:40 > 0:28:42one that I think is particularly persuasive.
0:28:42 > 0:28:47The actual words of the original Greek of the Gospel of St Matthew
0:28:47 > 0:28:49were "en te Anatole".
0:28:49 > 0:28:52And that literally translates as "rising in the East".
0:28:52 > 0:28:57But it's thought that "en te Anatole" actually had a very special meaning for ancient astronomers.
0:28:57 > 0:29:02It refers to the day of the year when a star reappears into view
0:29:02 > 0:29:04from behind the sun.
0:29:04 > 0:29:08As the sun moves against the constellations, it hides the stars behind it, of course.
0:29:08 > 0:29:12But on that day, that star will be briefly visible just
0:29:12 > 0:29:17before the sun rises, and that's known as the star's heliacal rising.
0:29:34 > 0:29:36It might seem an obscure phenomenon today,
0:29:36 > 0:29:40but heliacal risings were crucial events to many societies.
0:29:40 > 0:29:44The ancient Egyptians used the heliacal rising of Sirius
0:29:44 > 0:29:47to mark the beginning of the flood cycle of the Nile.
0:29:47 > 0:29:51And the Maoris of New Zealand still use the heliacal rising
0:29:51 > 0:29:55of the Pleiades star cluster to mark the beginning of their year.
0:29:56 > 0:29:58It's been suggested that
0:29:58 > 0:30:02the Star of Bethlehem that the wise men saw rising in the East
0:30:02 > 0:30:06was the heliacal rising of a star called Sa'd al-Malik,
0:30:06 > 0:30:08which we know as Alpha Aquarii.
0:30:08 > 0:30:13From the Arabic name, it translates as the "Lucky Star of the King",
0:30:13 > 0:30:16and that was seen as an omen for the birth of a new king.
0:30:18 > 0:30:22Now obviously, that's an occasion that would happen every year,
0:30:22 > 0:30:25so it would need to be coupled with other omens
0:30:25 > 0:30:27and signs to mark this specific event.
0:30:28 > 0:30:32But I think, given the importance of heliacal risings to ancient cultures,
0:30:32 > 0:30:34and also the name Sa'd al-Malik,
0:30:34 > 0:30:36which means the Lucky Star of the King,
0:30:36 > 0:30:41that puts forward a very persuasive case for this being the cause of the Star of Bethlehem.
0:30:50 > 0:30:54Another factor to take into account in the Star of Bethlehem story
0:30:54 > 0:30:57is the political situation in Judea at the time.
0:30:59 > 0:31:03Occupied by the Romans and with an unpopular king, people were
0:31:03 > 0:31:07desperate for change, so there was a hunger for an omen that might
0:31:07 > 0:31:09suggest a Messiah was on the way.
0:31:12 > 0:31:13It was a mixture of politics
0:31:13 > 0:31:18and religion that has been memorably depicted in film.
0:31:18 > 0:31:20Wah!
0:31:20 > 0:31:22I love The Life Of Brian.
0:31:22 > 0:31:27It's got a lot of resonances to the kind of chaotic situation
0:31:27 > 0:31:30of Judea in the first century,
0:31:30 > 0:31:31and also just at the time
0:31:31 > 0:31:34when Jesus was born.
0:31:34 > 0:31:36What's this, then?
0:31:36 > 0:31:39"People called Romanes, they go the house?"
0:31:39 > 0:31:43- It says, "Romans, go home!" - No, it doesn't.
0:31:43 > 0:31:47'The time of Jesus was a time of relative civil and social unrest.
0:31:47 > 0:31:49'Romans were occupying most of the known world
0:31:49 > 0:31:52'but there was a lot of discomfort, dissatisfaction,'
0:31:52 > 0:31:54economic hardship, there had been several famines,
0:31:54 > 0:31:57so all in all, things were not great for people, so people
0:31:57 > 0:32:02used to look to other sorts of groups for some kind of liberation or some kind of hope.
0:32:02 > 0:32:05One of the things I like about The Life Of Brian is that you do
0:32:05 > 0:32:08get this idea of all these would-be Messiahs.
0:32:08 > 0:32:12There's a line where a John Cleese character says...
0:32:12 > 0:32:13Hail, Messiah!
0:32:13 > 0:32:15I'm not the Messiah!
0:32:15 > 0:32:19I say you are, Lord, and I should know, I've followed a few.
0:32:19 > 0:32:21- ALL:- Hail, Messiah!
0:32:21 > 0:32:26And this is because the Pythons had really read Josephus
0:32:26 > 0:32:31and the historians of the time - they'd done their homework,
0:32:31 > 0:32:34so they knew that there was a lot of expectation
0:32:34 > 0:32:39and there were would-be Messiahs and prophets all over the place,
0:32:39 > 0:32:44because the end of the rule of Herod the Great was this time
0:32:44 > 0:32:51of great expectation and excitement and also just absolute desperation
0:32:51 > 0:32:56in terms of what the Romans were not doing for Judeans.
0:32:59 > 0:33:00Argh!
0:33:01 > 0:33:03'Later on, you had this curious
0:33:03 > 0:33:08'incident where Brian gets taken off by aliens in a spaceship,
0:33:08 > 0:33:10'and there's a bit of'
0:33:10 > 0:33:12a tongue-in-cheek reference to the star
0:33:12 > 0:33:16at the point, I think, that the star itself might have been an alien spaceship,
0:33:16 > 0:33:19rather than anything astronomical,
0:33:19 > 0:33:20so I just think that's really fun.
0:33:28 > 0:33:31Ooh, you lucky bastard!
0:33:31 > 0:33:34That brings us to our next candidate to be the Star of Bethlehem.
0:33:34 > 0:33:36It's one that had a reluctant champion,
0:33:36 > 0:33:39a familiar face to Sky At Night viewers.
0:33:40 > 0:33:42And this brings me on to my own suggestion,
0:33:42 > 0:33:45which I admit is not very convincing, but the best I can do.
0:33:45 > 0:33:51And I suggest that the Star of Bethlehem just could be due to two meteors.
0:33:51 > 0:33:54Just suppose the wise men were crossing the desert
0:33:54 > 0:33:58and they saw one of these really brilliant meteors moving ahead of them.
0:33:58 > 0:34:01It wouldn't last for long, but they'd certainly recognise
0:34:01 > 0:34:03that as being something very unusual.
0:34:03 > 0:34:05All right. Then a little later on,
0:34:05 > 0:34:09they see another meteor moving in the same direction with about the same brilliancy.
0:34:09 > 0:34:13Quite a coincidence, I agree, but not a too amazing one,
0:34:13 > 0:34:16in view of the fact that we do have showers of shooting stars.
0:34:16 > 0:34:20And that would explain, first of all, why nobody else saw it -
0:34:20 > 0:34:23it would have been visible only from that part of the globe -
0:34:23 > 0:34:25and also why nobody else could see it again
0:34:25 > 0:34:30when they went to look for it. It would only have lasted for a few seconds.
0:34:38 > 0:34:41The trouble with this idea is that meteors are common
0:34:41 > 0:34:44and even meteor showers are common.
0:34:44 > 0:34:47And especially with the dark skies of 2,000 years ago,
0:34:47 > 0:34:50I don't think that seeing one or two or even a whole host of meteors
0:34:50 > 0:34:52would have been considered that special.
0:34:52 > 0:34:56But there is an extension to this idea that might be worth considering.
0:34:56 > 0:35:01When you see a meteor, you're seeing a tiny dust grain burn up in our atmosphere.
0:35:01 > 0:35:04But larger objects do hit the Earth and when that happens,
0:35:04 > 0:35:07they leave quite a different visual impression.
0:35:07 > 0:35:10As these fireballs shoot across the sky,
0:35:10 > 0:35:15they seem to be heading for a touchdown on a specific point on Earth.
0:35:15 > 0:35:19And that could certainly be interpreted as a sign from the heavens.
0:35:19 > 0:35:22These events are so rare and so spectacular that they would
0:35:22 > 0:35:25certainly have attracted attention 2,000 years ago.
0:35:25 > 0:35:27They still do today.
0:35:27 > 0:35:29In February 2013,
0:35:29 > 0:35:32an object 20m across entered the Earth's atmosphere,
0:35:32 > 0:35:36travelling at 40,000mph.
0:35:36 > 0:35:40It burnt up, producing this spectacular fireball across the Russian sky.
0:35:42 > 0:35:46It exploded 30km above the city of Chelyabinsk.
0:35:46 > 0:35:51The explosion was more than 20 times as powerful as the atomic bomb
0:35:51 > 0:35:53detonated over Hiroshima.
0:35:53 > 0:35:58The shock waves injured 150 people and damaged thousands of buildings.
0:35:59 > 0:36:03Events like that at Chelyabinsk aren't actually that rare.
0:36:03 > 0:36:05We think that objects of that size hit the Earth
0:36:05 > 0:36:08two or three times a century.
0:36:08 > 0:36:11But most go unrecorded, as they happen over uninhabited areas.
0:36:11 > 0:36:14But you can see, looking at those videos,
0:36:14 > 0:36:17that if something had hit over the Middle East during the first century BC,
0:36:17 > 0:36:20it would have been interpreted as a miraculous sign
0:36:20 > 0:36:23and written into the legends of the time, and so that makes
0:36:23 > 0:36:27a meteorite strike our fourth candidate to be the Star of Bethlehem.
0:36:29 > 0:36:32Back on the quest for historical evidence for the star,
0:36:32 > 0:36:36I've directed my search several thousand miles further east,
0:36:36 > 0:36:39because the Babylonians weren't the only ancient civilisation to
0:36:39 > 0:36:42make astronomical observations.
0:36:42 > 0:36:46The Chinese were also making detailed records of everything
0:36:46 > 0:36:48they saw in the sky.
0:36:48 > 0:36:51Christopher Cullen is an expert in ancient Chinese astronomy.
0:36:53 > 0:36:56So Christopher, tell us what we're looking at here.
0:36:56 > 0:36:58We're looking at a chapter of the Han Shu.
0:36:58 > 0:37:02The Book of Han - a history of China written in about 100AD.
0:37:02 > 0:37:05And this is a record of phenomena seen in the sky.
0:37:05 > 0:37:09And how accurate a record is it?
0:37:09 > 0:37:11It was written a long time ago before what
0:37:11 > 0:37:14we would recognise as science, if you like, was happening.
0:37:14 > 0:37:16This was written by professionals.
0:37:16 > 0:37:20The Emperor maintains a staff of skywatchers, whose job is
0:37:20 > 0:37:23to be up there noting down everything that happens.
0:37:23 > 0:37:24And there's a reason for that,
0:37:24 > 0:37:28explained on the first page of this chapter - chapter 26.
0:37:28 > 0:37:34The stars and planets, all the lights up there, are a great control panel
0:37:34 > 0:37:37of indicator lights and if one of them starts blinking, or
0:37:37 > 0:37:42if a light appears where it's unexpected, that means something big is happening,
0:37:42 > 0:37:46because everything in the sky mirrors what's happening on the Earth.
0:37:46 > 0:37:49So it was the same idea, that this idea of portents
0:37:49 > 0:37:54- and omens of what was going on in the sky reflected human concerns. - Yeah, yeah.
0:37:54 > 0:37:56OK - so here's the question.
0:37:56 > 0:38:01- We're looking round about 7BC-4BC, round that sort of time.- Yeah.
0:38:01 > 0:38:04Is there anything of note in this book that we should
0:38:04 > 0:38:06look at in terms of bright objects?
0:38:06 > 0:38:10The nice thing about Chinese books is that they've got dates in them.
0:38:10 > 0:38:14So we turn through the chapter, looking at...everything's got a date there.
0:38:14 > 0:38:17And we come to near the end of the chapter.
0:38:17 > 0:38:19And we see in the second year - that's 5BC...
0:38:19 > 0:38:225BC, OK, well that's ballpark.
0:38:22 > 0:38:26Second month - that's lunar month, this is early March to early April.
0:38:26 > 0:38:29- Which again...- Yeah? All right? Nice.- ..sounds good.
0:38:29 > 0:38:35A broom star appeared in the constellation of the Ox for more than 70 days.
0:38:35 > 0:38:37- Will that do you? - Well, that's pretty good.
0:38:37 > 0:38:40By broom star, presumably we're talking about a comet?
0:38:40 > 0:38:42Most of the time, I think.
0:38:42 > 0:38:46When you see records of movement and statements about how long it was,
0:38:46 > 0:38:48like a tail, it's usually called a broom star.
0:38:48 > 0:38:51I'd go probably for a comet, but it doesn't have to be.
0:38:51 > 0:38:55I'm just trying work out, could it be something else - could it be a supernova, for example?
0:38:55 > 0:38:58I would not say it was impossible it could be a supernova.
0:38:58 > 0:39:00Of course, to prove it was a supernova,
0:39:00 > 0:39:04what we'd like to do is to find the actual remnant,
0:39:04 > 0:39:07the nebula left today, as we can with the Crab Nebula.
0:39:07 > 0:39:10But there's no remnant been proposed for this.
0:39:10 > 0:39:16- And 70 days - that gives us quite a wide area of time.- Mmm.- OK.
0:39:16 > 0:39:19And they say later, they say the fact that it was up there for
0:39:19 > 0:39:21so long means that it really shows something big.
0:39:21 > 0:39:25So much so that the Emperor was actually persuaded for a short
0:39:25 > 0:39:28while to start recounting the years of his reign from this year.
0:39:28 > 0:39:30So not the second year, now it's now the first year
0:39:30 > 0:39:33because something so important has happened.
0:39:33 > 0:39:37- Wow - that is really interesting. So, big political news.- Yeah.
0:39:37 > 0:39:39This is 5BC.
0:39:39 > 0:39:43- This broom star, this comet, would have been seen in the Middle East as well.- Absolutely.
0:39:43 > 0:39:46How accurate do you think these records are?
0:39:46 > 0:39:48Because we're going back a long way.
0:39:48 > 0:39:51Are you confident in the dates, for example?
0:39:51 > 0:39:56Yes, I am. Basically, Chinese dates in history are reliable to the year,
0:39:56 > 0:40:01from about the middle of the 9th century BC, this is fairly well established.
0:40:01 > 0:40:04Sometimes, you will find someone's miscopied a month.
0:40:04 > 0:40:08But to check that, look at the next entry - the next entry tells us
0:40:08 > 0:40:12basically that a little later, Jupiter was seen moving
0:40:12 > 0:40:14through a certain constellation
0:40:14 > 0:40:16and they say it did this retrograde loop.
0:40:16 > 0:40:20It's where you do a calculation to check, you find that yeah,
0:40:20 > 0:40:23that date is when Jupiter would have done a retrograde loop.
0:40:23 > 0:40:27There are other things like the moon going in front of particular star.
0:40:27 > 0:40:28You can check - and it did.
0:40:28 > 0:40:31Christopher, that's absolutely fascinating.
0:40:31 > 0:40:33This is a whole new area, line of inquiry
0:40:33 > 0:40:36that I didn't even knew existed, so thank you very much indeed.
0:40:36 > 0:40:40- It's been a great pleasure. - It's been an absolute treat to look at this. Thank you.- Thanks.
0:40:40 > 0:40:44So far, we've learned that the Star of Bethlehem may have been
0:40:44 > 0:40:46a number of things -
0:40:46 > 0:40:49a bright supernova,
0:40:49 > 0:40:53a rare alignment of planets,
0:40:53 > 0:40:55a meteor or the rising of a star.
0:40:56 > 0:41:00There are only two to go and the Chinese records immediately raise
0:41:00 > 0:41:04another prime candidate - a comet.
0:41:06 > 0:41:10We asked planetary scientist Alan Fitzsimmons to explain why
0:41:10 > 0:41:13he thinks the Star of Bethlehem could have been a comet.
0:41:15 > 0:41:17I think comets are fascinating objects.
0:41:17 > 0:41:22I always have done and that's why I've worked on them all my life.
0:41:22 > 0:41:26Now historically, the appearance of a comet has been seen as an omen
0:41:26 > 0:41:27of events here on Earth
0:41:27 > 0:41:30and that's why I think it could have been a comet
0:41:30 > 0:41:34that took on religious significance as the Star of Bethlehem.
0:41:57 > 0:42:00So, the idea that a comet was the Star of Bethlehem
0:42:00 > 0:42:04has been around for hundreds, if not thousands of years.
0:42:04 > 0:42:07In fact, it was first written down, to our knowledge,
0:42:07 > 0:42:11by the Christian writer Origen in the year 248 AD.
0:42:11 > 0:42:14But this is the picture that really puts comets in the frame.
0:42:14 > 0:42:20It's by Giotto, the finest painter of his time, back in 1305.
0:42:20 > 0:42:25It shows a typical Nativity scene, based around the infant Jesus,
0:42:25 > 0:42:26and above the stable,
0:42:26 > 0:42:30poised majestically in the sky, is a beautiful comet.
0:42:34 > 0:42:37Comets come from the very outer edges of the solar system.
0:42:37 > 0:42:42They are the frozen leftovers from the formation of the planets.
0:42:42 > 0:42:46We might not know they existed at all if they weren't occasionally
0:42:46 > 0:42:49sent catapulting into the inner solar system.
0:42:50 > 0:42:51As they approach the sun,
0:42:51 > 0:42:55they reveal themselves by putting on the most extraordinary show,
0:42:55 > 0:43:00and the closer they get to the sun, the brighter they get.
0:43:00 > 0:43:03So, when I first read these accounts by ancient Chinese
0:43:03 > 0:43:06astronomers of a comet that could be seen for 70 days
0:43:06 > 0:43:08in the early morning skies,
0:43:08 > 0:43:12I knew it must be incredibly bright for part of that time.
0:43:12 > 0:43:15Also, if it's in the morning sky, it's near the sun
0:43:15 > 0:43:19and those two things together make me think of sungrazing comets.
0:43:19 > 0:43:24Here we've got a set of images and wonderful movies of Comet ISON,
0:43:24 > 0:43:27a sungrazing comet that appeared just two years ago.
0:43:27 > 0:43:30You can see it does get incredibly bright.
0:43:33 > 0:43:36The reason that sungrazers get so bright
0:43:36 > 0:43:39is that they get red hot as they pass close to the sun.
0:43:41 > 0:43:45In a normal comet far away from the sun, the sun's heat is enough
0:43:45 > 0:43:50to vaporise the ice, that streams away as gas, also releasing
0:43:50 > 0:43:55small dust particles, and they go into forming the tails of the comet.
0:43:55 > 0:43:59In a sungrazing comet, as it approaches the sun,
0:43:59 > 0:44:03everything starts getting red hot and everything vaporises.
0:44:03 > 0:44:09The ice, the comet dust, even any rock that could be in there.
0:44:09 > 0:44:12Everything goes and in doing so,
0:44:12 > 0:44:16that's what makes the sungrazing comet so bright.
0:44:20 > 0:44:24Many of the chunks that we see in the satellite images are small,
0:44:24 > 0:44:27just 10 to 15 metres across, and we can't really see them
0:44:27 > 0:44:31from Earth, but now and then, a much bigger chunk comes along.
0:44:35 > 0:44:40This is a picture of Comet McNaught, the Christmas comet of 2006
0:44:40 > 0:44:43and one of the brightest comets to be seen from Earth
0:44:43 > 0:44:45over the past 1,000 years.
0:44:45 > 0:44:49So bright because it passed close to our sun.
0:44:49 > 0:44:53You can see the tail here, pointing downwards towards the horizon,
0:44:53 > 0:44:56as if indicating that something is happening over there.
0:44:56 > 0:45:00Surely if a comet like this had appeared in the Middle Eastern skies
0:45:00 > 0:45:04some 2,000 years ago, the Magi would have been drawn towards that
0:45:04 > 0:45:09direction and maybe ended up in a stable in the town of Bethlehem.
0:45:12 > 0:45:14There are other details of the Nativity story
0:45:14 > 0:45:17that suggest that a comet could have been the star.
0:45:19 > 0:45:24Matthew's Gospel implies that the star was seen twice.
0:45:24 > 0:45:26Once to bring the Magi to Jerusalem,
0:45:26 > 0:45:29a journey that must have taken weeks, if not months.
0:45:29 > 0:45:33Then a second time to lead them to Bethlehem.
0:45:33 > 0:45:36That behaviour is typical of many comets.
0:45:39 > 0:45:44So, this is a first edition of Newton's Principia from 1687
0:45:44 > 0:45:48and right at the front of the book we have this beautiful diagram
0:45:48 > 0:45:53showing the path of a great comet that Isaac Newton himself saw.
0:45:53 > 0:45:57You can see how it appeared firstly in November 1680
0:45:57 > 0:45:59on its way into the sun.
0:45:59 > 0:46:02It disappeared for a couple of weeks when it was closest to the sun,
0:46:02 > 0:46:07then reappeared in our skies in early 1681.
0:46:07 > 0:46:11This showed that comets followed regular paths under the influence
0:46:11 > 0:46:15of the laws of gravity that Isaac Newton had discovered.
0:46:15 > 0:46:19It's this behaviour of the comet that could explain how
0:46:19 > 0:46:23the Star of Bethlehem appeared twice to the Magi.
0:46:23 > 0:46:26So putting it all together, there is a bright comet
0:46:26 > 0:46:30seen at the right time by Chinese astronomers.
0:46:31 > 0:46:35If the Star of Bethlehem appeared twice, then comets can do that too.
0:46:35 > 0:46:38Comets have been seen as omens of important events
0:46:38 > 0:46:40for hundreds or thousands of years
0:46:40 > 0:46:44and a comet tail pointing down towards the eastern horizon
0:46:44 > 0:46:47could imply something important was happening there.
0:46:47 > 0:46:50Altogether, if there was a Star of Bethlehem,
0:46:50 > 0:46:52I think it could have been a comet.
0:47:02 > 0:47:06A comet just suddenly popping up always created a sense of instability
0:47:06 > 0:47:08in what was going on.
0:47:08 > 0:47:12Unexpected and often quite frightening.
0:47:12 > 0:47:14It's not a good omen.
0:47:14 > 0:47:18Shortly before the death of Nero, comets were seen in the sky.
0:47:18 > 0:47:21Julius Caesar, at the time of his murder.
0:47:21 > 0:47:24This is not just the Babylonians,
0:47:24 > 0:47:27this is the Romans, the Greeks, it's everybody.
0:47:27 > 0:47:31In other contexts, comets are not necessarily bad news.
0:47:31 > 0:47:34So, there is a text in the Book of Isaiah in the Jewish Scriptures that
0:47:34 > 0:47:39talks about a star falling from the heavenly realm into the underworld.
0:47:39 > 0:47:43This is a bad god, a bad divine being who is being sent
0:47:43 > 0:47:45out of the heavenly realm and into the underworld,
0:47:45 > 0:47:46so it's bad news for him,
0:47:46 > 0:47:49but good news for the rest of humankind.
0:47:49 > 0:47:51In the same way, for those that think
0:47:51 > 0:47:54the Star of Bethlehem is a comet, it's bad news for King Herod,
0:47:54 > 0:47:57but good news for the followers of Jesus.
0:48:00 > 0:48:04With the addition of a comet, that leaves one final candidate.
0:48:06 > 0:48:08Maggie has been to meet Mark Kidger,
0:48:08 > 0:48:11who believes the Chinese record in 5BC is not a comet,
0:48:11 > 0:48:13but something much more intriguing.
0:48:15 > 0:48:19He believes it was an event called a nova.
0:48:19 > 0:48:23If he's right, the Star of Bethlehem is still lurking in the sky,
0:48:23 > 0:48:25exactly where the Chinese saw it.
0:48:40 > 0:48:44And you're saying that the Star of Bethlehem is still in the star field?
0:48:44 > 0:48:48Yes, if my ideas of the Star of Bethlehem are right,
0:48:48 > 0:48:52it's still there, round about where it is marked with the arrow.
0:48:52 > 0:48:54I can't see anything bright enough in there
0:48:54 > 0:48:56that could possibly be the Star of Bethlehem.
0:48:56 > 0:49:00Exactly, because now the Star of Bethlehem is very, very faint.
0:49:00 > 0:49:02You may not even be able to see it
0:49:02 > 0:49:06with the biggest telescope in the world, but what we do know
0:49:06 > 0:49:09from the Chinese records is that it was pretty bright.
0:49:09 > 0:49:13The Chinese say that they saw it for 70 days.
0:49:13 > 0:49:15They just give this position in the sky
0:49:15 > 0:49:18close to Alpha and Beta Capricorni.
0:49:18 > 0:49:20It's a star that appeared,
0:49:20 > 0:49:23stayed visible to the naked eye for 2.5 months.
0:49:23 > 0:49:27The Chinese monsoon came, the Chinese lost it
0:49:27 > 0:49:30and it faded away in that time.
0:49:30 > 0:49:33When they were able to look at the sky again, it had disappeared.
0:49:33 > 0:49:37So, for me, there is one simple, obvious candidate for that,
0:49:37 > 0:49:39which is a nova.
0:49:39 > 0:49:41A nova? Describe to me what a nova is.
0:49:41 > 0:49:46Right, a nova is something very much smaller than a supernova.
0:49:46 > 0:49:49It's a pair of stars, a binary star,
0:49:49 > 0:49:54a big old red giant we see there, arriving at the end of its life,
0:49:54 > 0:49:56and a little white dwarf star
0:49:56 > 0:49:59that's already been a red giant and it's died.
0:49:59 > 0:50:03What is happening is, this white dwarf star is a cannibal
0:50:03 > 0:50:06and material from the red giant is spiralling down
0:50:06 > 0:50:07onto the white dwarf.
0:50:07 > 0:50:11It falls on, gets hotter and hotter, accumulates and accumulates
0:50:11 > 0:50:14and then suddenly, boom!
0:50:14 > 0:50:18You get to a critical point, there is a critical mass
0:50:18 > 0:50:21and the whole thing explodes and a cloud of gas
0:50:21 > 0:50:26and dust goes out into space and it is very bright for a time,
0:50:26 > 0:50:30months, sometimes only for a few days and then fades away
0:50:30 > 0:50:36and disappears and then slowly accretes material on top again.
0:50:36 > 0:50:39Then 10 years, 100 years, 1,000 years,
0:50:39 > 0:50:41maybe even 10,000 years later,
0:50:41 > 0:50:44boom again as the material builds up.
0:50:44 > 0:50:47I suppose it's got to get that critical mass before it goes boom!
0:50:47 > 0:50:49It varies from nova to nova?
0:50:49 > 0:50:52It varies from nova to nova, it depends how much is falling
0:50:52 > 0:50:55onto the small star, how quickly it's happening,
0:50:55 > 0:50:57how big the small star is.
0:50:57 > 0:51:01It gets hotter and hotter and hotter and suddenly, crisis and boom!
0:51:01 > 0:51:05On that basis, if it goes boom every so often,
0:51:05 > 0:51:09- it means we could again see the Star of Bethlehem in the future?- Exactly.
0:51:09 > 0:51:13That is one of the beauties of this theory, because as you said,
0:51:13 > 0:51:17you cannot see the star there, but one day, if you are patient and
0:51:17 > 0:51:19keep observing the sky, that star,
0:51:19 > 0:51:23if it really was a nova, will reappear.
0:51:23 > 0:51:25It might not be in time for this Christmas special
0:51:25 > 0:51:29and it might not be for next year's Christmas special,
0:51:29 > 0:51:32but 1,000 years - it may happen.
0:51:32 > 0:51:34It's a neat idea
0:51:34 > 0:51:38and it's possible that the Chinese records are of a star going nova.
0:51:40 > 0:51:45But we still need to explain why this particular effect was so special.
0:51:45 > 0:51:47Nova aren't particularly rare.
0:51:47 > 0:51:52Why would this one draw the three wise men to follow a star?
0:51:52 > 0:51:57OK, so, the first thing, it was bright. It wasn't just any nova.
0:51:57 > 0:52:01It's the sort of nova you only see once every few hundred years.
0:52:01 > 0:52:02That's one thing.
0:52:02 > 0:52:05The second thing is, it followed a series
0:52:05 > 0:52:07of other interesting events.
0:52:07 > 0:52:12We had that triple conjunction that was observed in 6BC when Jupiter
0:52:12 > 0:52:17and Saturn came close together and separated and came close again,
0:52:17 > 0:52:20three times over a period of months.
0:52:20 > 0:52:23Jupiter, the King of the Gods, symbol of kings.
0:52:23 > 0:52:25Saturn, the changer of ages.
0:52:25 > 0:52:27If you are a Persian astrologer,
0:52:27 > 0:52:30that sort of thing would have been tremendously significant.
0:52:30 > 0:52:32It marks something happening, something coming up?
0:52:32 > 0:52:38Something was coming up and then just over a year later, bang!
0:52:38 > 0:52:43You get the brightest nova you have seen in the sky in centuries.
0:52:43 > 0:52:47Now is the moment. Get those camels, wagons roll!
0:52:47 > 0:52:48OK, yes!
0:52:48 > 0:52:50So, in terms of its position,
0:52:50 > 0:52:53would it have drawn the Magi in the right direction?
0:52:53 > 0:52:54That's the beauty of this theory.
0:52:54 > 0:52:58It does everything that you need, just the stars in their courses,
0:52:58 > 0:52:59behaving naturally.
0:52:59 > 0:53:04Matthew's Gospel says that the Magi saw the star at its rising.
0:53:04 > 0:53:06It would've been in the East at dawn.
0:53:06 > 0:53:09They took six weeks, if they were in a real hurry,
0:53:09 > 0:53:13maybe two months to reach Jerusalem. They spoke to King Herod.
0:53:13 > 0:53:16Two months later, where would the star be?
0:53:16 > 0:53:18It rises a little bit earlier each night,
0:53:18 > 0:53:21then it would have been due south at dawn.
0:53:21 > 0:53:23Right over the town of Bethlehem,
0:53:23 > 0:53:26and they really would have followed it towards Bethlehem.
0:53:26 > 0:53:29It really would've guided them on that last leg of their journey.
0:53:29 > 0:53:31So, to you, all the evidence adds up
0:53:31 > 0:53:34and to you, the Star of Bethlehem was a nova?
0:53:34 > 0:53:36This is just the simplest theory.
0:53:36 > 0:53:39That's the beauty of it. It's very, very simple.
0:53:39 > 0:53:42The stars in their courses do everything that you need.
0:53:42 > 0:53:47And it's a natural event, but it's a quite rare natural event,
0:53:47 > 0:53:50and that's the beauty of it. It's what I like about the nova theory.
0:53:50 > 0:53:51Well, it's a nice theory,
0:53:51 > 0:53:54so thank you very much for describing it to me.
0:53:54 > 0:53:56- And thank you very much indeed to you.- Thank you.
0:54:13 > 0:54:16We now have six plausible candidates
0:54:16 > 0:54:19that could have given rise to the Star of Bethlehem.
0:54:19 > 0:54:24A nova or supernova,
0:54:24 > 0:54:26a comet or meteor,
0:54:26 > 0:54:28the rising of a star,
0:54:28 > 0:54:31or an alignment of the planets.
0:54:31 > 0:54:34And now Chris, and I have to assess the evidence
0:54:34 > 0:54:37and choose what we think was the most likely cause.
0:54:37 > 0:54:38What do you reckon, Maggie?
0:54:38 > 0:54:41I think, rather than homing in on what I think it is,
0:54:41 > 0:54:43- I'd rather home in on what I think it isn't.- All right.
0:54:43 > 0:54:46Meteors fall all the time. I don't think that would be enough to cause
0:54:46 > 0:54:48- people to leave their home and travel afar.- Right.
0:54:48 > 0:54:51And even if we had a really spectacular one like Chelyabinsk
0:54:51 > 0:54:53we would have seen more records.
0:54:53 > 0:54:55Someone might even have found the meteorite...
0:54:55 > 0:54:58- Yeah, that would be fun! - ..if it touched down.
0:54:58 > 0:55:00- It seems unlikely to me.- Yeah. Good. Down to five.
0:55:00 > 0:55:01What about the supernova?
0:55:01 > 0:55:04This is the Christmas card Star of Bethlehem.
0:55:04 > 0:55:07It's a bright new star that hangs in the sky.
0:55:07 > 0:55:10There's poetry there as well - the death of a star marks
0:55:10 > 0:55:13the birth of a king. And it would have been quite spectacular.
0:55:13 > 0:55:16The problem is we don't see a remnant from this supernova.
0:55:16 > 0:55:19When there has been one in the last few thousand years, we see
0:55:19 > 0:55:20the nebula that's left over,
0:55:20 > 0:55:24like the Crab, which is beautiful, from 1,000 years ago.
0:55:24 > 0:55:26- I think there's a gap there. - I'm happy to dismiss.
0:55:26 > 0:55:29Fine. Let's also talk about this one. This is the rising of the star.
0:55:29 > 0:55:31It happens every year.
0:55:31 > 0:55:33Why would this mark a significant event?
0:55:33 > 0:55:36Right. We're either missing a few thousand Messiahs, or I agree,
0:55:36 > 0:55:40- I think this is the sort of thing you use to mark the New Year.- Yes.
0:55:40 > 0:55:44Right? Or to mark a significant annual event - it's not a one-off.
0:55:44 > 0:55:46- Yes.- And so, I think that can go.
0:55:46 > 0:55:49'We are now down to our three final possibilities -
0:55:49 > 0:55:51'the nova,
0:55:51 > 0:55:53'the comet
0:55:53 > 0:55:55'and the planetary conjunction.
0:55:55 > 0:55:58'It's possible to make a compelling case for each of them.
0:55:58 > 0:56:00'At this point it's down to the piece
0:56:00 > 0:56:02'of evidence we choose to put the most weight on.
0:56:02 > 0:56:05'We know that the triple conjunction happened
0:56:05 > 0:56:08'and was recorded by astronomers in the Middle East.
0:56:08 > 0:56:11'But I wonder if this subtle event
0:56:11 > 0:56:13'would really have been significant enough.'
0:56:13 > 0:56:16I don't think it would've been that spectacular in the sky.
0:56:16 > 0:56:18Yes, it's almost the opposite.
0:56:18 > 0:56:20Planets get close to each other all the time - we had Venus
0:56:20 > 0:56:23and Jupiter close to each other last month in the morning sky.
0:56:23 > 0:56:26So the argument that it is this conjunction rests on this idea
0:56:26 > 0:56:29that there is something significant about the fact that
0:56:29 > 0:56:31it's Jupiter and Saturn, the old king and the new king,
0:56:31 > 0:56:33that it rests on the fact it's in Pisces,
0:56:33 > 0:56:35which according to one text
0:56:35 > 0:56:38is associated with this particular patch of land.
0:56:38 > 0:56:41But the thing is, we don't know what the right astrology was.
0:56:41 > 0:56:45Astrologers don't agree with each today, let alone 2,000 years ago.
0:56:45 > 0:56:47And you can pretty much support any story you like.
0:56:47 > 0:56:50Well, on that basis, I think this one goes as well.
0:56:50 > 0:56:53Yep. So that leaves us with what? A nova and a comet.
0:56:53 > 0:56:56The thing that both of these have going for them, I think,
0:56:56 > 0:56:59is that they are described, in that Chinese observations.
0:56:59 > 0:57:00I quite like the idea of a nova
0:57:00 > 0:57:03because I love the idea of a nova, it might appear again.
0:57:03 > 0:57:06The whole process can reignite and it could reappear in our night sky.
0:57:06 > 0:57:07There is no evidence against it,
0:57:07 > 0:57:09but there's not much evidence, for me, for it.
0:57:09 > 0:57:10My fear with the comet is that
0:57:10 > 0:57:13in the past, many people have associated comets with doom.
0:57:13 > 0:57:16- That's true.- And so, why would you associate a comet with the birth
0:57:16 > 0:57:18of a Messiah, a new king?
0:57:18 > 0:57:21- We should be careful about taking what we think about comets...- Yes.
0:57:21 > 0:57:23..or what Westerners thought about comets and imposing it...
0:57:23 > 0:57:26That's right and we don't know how far that belief goes.
0:57:26 > 0:57:30What the comet has over the nova to me, is that it looks like it is pointing.
0:57:30 > 0:57:32- The comet has a direction.- Yes.
0:57:32 > 0:57:35It's an arrow. They're also beautiful and noteworthy,
0:57:35 > 0:57:37so I can imagine following that.
0:57:37 > 0:57:40And I think it can do the magical thing of disappearing as it
0:57:40 > 0:57:42- goes round the back of the sun and coming back again.- Yes.
0:57:42 > 0:57:45So there's a very straightforward explanation of why it would be
0:57:45 > 0:57:47- seen twice.- I like the independent verification,
0:57:47 > 0:57:50the fact that other sources - nothing to do with the story,
0:57:50 > 0:57:54saw it. It was significant. It was commented on across the world.
0:57:54 > 0:57:57Who knows, that could've got into legend and ended up in the story.
0:57:57 > 0:57:59If it's real, for me, it's a comet.
0:57:59 > 0:58:02- I'd be happy to go with a comet. - All right.
0:58:02 > 0:58:05That's it, then. The Sky At Night verdict is that
0:58:05 > 0:58:09the Star of Bethlehem was most probably a comet.
0:58:11 > 0:58:13That's it for this month.
0:58:13 > 0:58:16We're off air next month to make way for Stargazing Live.
0:58:16 > 0:58:17We'll be back in February.
0:58:17 > 0:58:20But in the meantime, you can still check out the website to find
0:58:20 > 0:58:24Pete's guide to the highlights of January's night sky and to find out
0:58:24 > 0:58:25how to find a message in the stars
0:58:25 > 0:58:28with the Whispering Stars messaging service.
0:58:28 > 0:58:32- In the meanwhile, get outside and get looking up.- Goodnight.