The History and Significance of Constellations

Welcome to the Royal Society and my name is Felicity Henderson. I'm the Events Manager here in our new Centre for History of Science. Those of you who've been here before and I recognise many friendly faces, very nice to see you. back again and you'll realise that we've had some refurbishment work done in this room. We've got our nice new screen so it will no longer be difficult for you to see the pictures at the front and we've got... some cooling put in and so hopefully it's a new and improved experience. So it's my very happy duty today to introduce to you our first speaker in our new autumn series of lunchtime lectures and today we have Mr Ian Ridpath. Ian got interested in astronomy at an early age like probably many other people through watching. Patrick Moore and so he's been hooked ever since and he's lucky enough to be able to write popular books about astronomy and he tells me that he's written a book about this very topic that he's speaking about today which is called Star Tales and he's also the editor of the Oxford Dictionary of Astronomy as well so if you need to look anything up then I highly recommend that volume. But that's enough from me, and so I'd like to welcome Ian to the podium to speak about pictures in the sky, the origin and history of the constellations. Thank you. Okay, well, good afternoon, everybody. It's nice to see there's a good turnout. Thank you all for giving up your lunch times. Well, the constellations are something that we pretty much take for granted, aren't they? I mean, we tend to assume that they've always been there. there like the stars themselves. But in fact they haven't because they are a product of human imagination. They're in fact one of the earliest attempts to impart some form of... order on the universe around us. And being a human invention, there's a story, like all human inventions, about how they came to be. And that's the story that I'm going to tell you today. And it's a story that goes back over 3,000 years. And it involves a trail of many thousands of miles around the Mediterranean as we follow the route by which the ancient constellations were handed down to us. And along the way, I'll introduce you to a story that goes back over 3,000 years. you to some more recent astronomers and explorers who added their own constellations to the originals, and we'll meet some other constellations that didn't make the final selection. And at the end, I'll direct you to a website which will tell you more about what I've been saying, so if you get lost, don't worry. Well, today there are 88 constellations recognized in all, and if we can have the lights down, please. And they fit together like pieces of a jigsaw to... Not that much, I can't see my nose. Thank you. And they fit together like pieces of a jigsaw to fill the entire sky from the north celestial pole to the south. And their names and their boundaries are now fixed by international agreement, so you can't just add new constellations or change their shape. and sizes to suit yourself, but it's only been like that within the past century. Originally, constellations were simply regarded as imaginary pictures without rigid boundaries, sometimes even overlapping each other and sharing the same image. the same stars. And I'm going to try to explain how we ended up with these 88 constellations and who decided on the boundaries, and along the way I'll explain how the names of certain stars came about as well. Well, let's start our journey by turning the clock back and imagining the scene in a village thousands of years ago. The villagers are gathered around a communal fire. Dinner is over and the fire is dying down. one of the village elders begins to tell stories. And these are stories that have been handed down through generations by word of mouth, which is how stories were transmitted in the days before writing. And the stories are about gods, mythical heroes, fabulous beasts. There's a story about a beautiful princess saved by a dashing hero. A lecherous god who turns himself into animals to abduct beautiful girls and boys. And a giant hunter who was stung to death by a scorpion. And to illustrate these tales, the storyteller uses the stars. And I think this is how the first constellations came into being. The sky was like a great projection screen. and the audience were invited to imagine the characters in the various tales among the stars, like a picture book in the sky. So I think that in most cases, the stories came first, and patterns in the sky were visualized to fit. those stories. And in a lot of cases, it was quite an unconvincing force fit. And this explains why many of the constellations really don't look anything like what they're supposed to represent, which of course is something that always battles newcomers. Mind you, some of the constellation shapes are quite a good fit. You might well see a lion in the stars of Leo, and a scorpion in the stars of Scorpius. But I don't think anyone has ever tried to argue that you can see a goat with a tail like a fish among the stars of Capricornus, or that Cassiopeia looks very much like a woman sitting in a chair and combing her hair. So I think it's important to realize that the original constellations weren't intended to be taken as literal representations. They were simply allegorical. Well, the constellations that everyone uses today have come down to us. from the Greeks, although of course other cultures imagined completely different pictures in the sky. The Chinese, for example, had over three times as many constellations as we do, mostly quite small, and they don't look anything like the constellations that we know. Well here's part of a chart that was found at a place called Dunhuang on the Silk Road in China, and it shows the Chinese constellations around the north pole of the sky, dating from about the same era as the ancient Greeks. Greek astronomer Ptolemy. Now you should be able to make out the familiar shape of the plough. Can you see it down there at the bottom? But even an experienced astronomer would be hard-pressed to recognize much else. Now this is in fact a fantastically interesting document. It's over 1300 years old and it's the oldest surviving star chart drawn on paper because of course the Chinese also invented paper. And it's in the British Library and if you want to find out more about about it, go onto their website and they've got loads more about it there. But for this talk I'm not going to say any more about Chinese constellations, I'll be concentrating just on the Western tradition. Now one thing we now know that the ancient sky watchers didn't is that the stars in a constellation have no physical connection with each other. Up until only a few centuries ago it was thought that stars were like lights stuck on an invisible sphere surrounding the Earth. But thanks to modern science, we know that stars are glowing balls of gas, like the sun, and they're all at different distances from us, so far away that their light takes many years or even centuries to reach us. And the patterns they form are purely a matter of chance, like the W shape of Cassiopeia here. Well, in Greek literature, the first mention of constellations dates back to about 700 BC in the works of Homer and Hesiod, although they mentioned only a handful of constellations and stars, such as the Great Bear, Orion, the Pleiades star cluster, I mean, at that time, the Pleiades was regarded as a separate constellation in its own right, and the dog star Sirius. It's not until about 350 BC that there is evidence for a reasonably full set of Greek constellations, and that comes from an astronomer called Eudoxus. Now, his original writings are lost, but another Greek called Aratus turned them into a poem called The Phenomena around 275 BC, and that does still exist. And in this poem, Aratus gave us a complete guide to the constellations known to the ancient Greeks. Well, unfortunately, the poem's a bit difficult to follow in places. Here's an example. example describing the bears and Draco the dragon around the North Celestial Pole. I know it doesn't look much like a poem, but presumably it rhymed a bit better in the original Greek. If there's anyone here who can speak Greek, perhaps they can tell me afterwards. Well, we can get our first look at pictures of the ancient Greek constellations described by Aratus on this sculpture of Atlas. Now, he's not holding up the earth, as we might normally think, but it's the heavens. And what he's holding here is actually the... oldest known celestial globe. And the statue is called the Farnese Atlas because it was bought by an Italian cardinal called Farnese. And it's thought to be a Roman copy of an older Greek original showing the same constellations as Aratus described in his poem. And in this close-up you might be able to see the sinuous shape of Hydra the water snake, which is actually the largest constellation in the sky, with Crater the Cup and Corvus Corvus. the crow on its back. And the crow, the cup, and the water snake are linked in a tale from Greek myth. And below left of it is Argo, the ship of the Argonauts, which of course features in a major epic from Greek myth. And to the right of that is Centaurus, who represents Chiron, the wise centaur. And of course, being a globe, everything is back to front by comparison with the way we see it from Earth. And to see everything the right way round, you would have to go back and forth between the two. would have to be inside the globe. And in the area around Atlas's head, there aren't any constellations at all, because that's the area around the South Pole that couldn't be seen from the Mediterranean. So the figures on this globe are pictures in the sky the way the ancient Greek people would have imagined them. Well, the first truly scientific description of the ancient Greek constellations comes from an encyclopedia of astronomy and mathematics called the Almagest, which is one of the great books of antiquity. And it was written around A.D. 1100. 150 by Ptolemy, who's usually regarded as a Greek scientist, although he worked at Alexandria in northern Egypt, near the mouth of the Nile, rather than in Greece itself. And the Almagest contained a catalogue of about about a thousand stars divided into 48 constellations. And it's generally thought that it's based on a catalogue compiled by an earlier Greek called Hipparchus, which hasn't survived. Ptolemy's original manuscript hasn't survived either, but it was laboriously copied and recopied by hand, and we still have some of those copies. And with the invention of printing in the 15th century, it was possible to make many copies quite quickly. And here's a page from the first. printed edition of the Almagest from 1515. And the columns on the right have got the coordinates and the brightness of the star, but what seems odd to us now is this section on the left where each star is identified by a long-winded description of its position in the overall constellation shape. Now these days we'd give each star a catalogue number, but Ptolemy didn't do that because he still regarded the constellations as real pictures. For example, this description of a star in Taurus, the reddish one on the southern eye. That's what Ptolemy called the star we know as Aldebaran. But Aldebaran is an Arabic name that came later. Here's another one, this time in Orion. The bright reddish star on the right shoulder. We now call that Betelgeuse. Or the bright star in the left foot. That's Rigel, also in Orion. But again, the Greeks didn't have a name. name for it. And I find it amazing that three of the brightest and most prominent stars in the sky didn't have names in Greek times, or at least if they did, they weren't mentioned by Ptolemy. For some reason, the Greeks weren't particularly interested in naming individual stars. Well, Ptolemy was the last of the ancient Greek astronomers, and after him there's a long gap during which the center of astronomy moved away from Greece into the Middle East, and it's at this stage that the Arabs come into the story. highlight from this era is provided by a Persian astronomer called Al-Sufi, or Azofi in its Latinized form. And Al-Sufi's masterwork was called The Book of the Fixed Stars, which was a revised and updated version. of Ptolemy's Almagest. And even though it was published 800 years after the Almagest, it contained the same constellations as the Greeks knew. But Al-Sufi added rather nice illustrations of each constellation, and of course they weren't done in Greek style, but Islamic style. And here you can see Orion in his Islamic dress, what the Greeks imagined as his shield has become a long sleeve. And Al-Sufi's book showed each constellation in two ways. one as it's seen from the earth on the left there and the other one as seen on a celestial globe where it appears back to front. And since this was still in the days before printing all books were in manuscript form so they had to be copied individually by hand and the illustrations were different in each manuscript. And this picture is actually from a copy made in the 13th century 300 years after the book was first written. Now to stop and put this into context, we're in the Middle Ages in Europe and by this time the Arab Empire has expanded through North Africa and into Spain and it was through this route of the Arabs coming into Spain that the ancient Greek works were reintroduced into Western Europe from the 11th century onwards. And the Spanish city of Toledo in particular is said to have become a veritable translation factory during the 12th century, and scholars flopped there from all over Western Europe. to study the marvellous new works, not just on astronomy, but mathematics and all other branches of science. And the most prolific of these translators was Gerard of Cremona, an Italian who went to Toledo in his late twenties, specifically to study the Almagest, and ended up spending the rest of his life there, translating over 70 different works of all kinds. And it was Gerard's Latin translation of the Almagest that formed the basis for the first printed edition, which I share with you. showed you a couple of slides ago. And the language that Gerard and his colleagues translated the Arabic manuscripts into wasn't Spanish or English, but Latin, because of course Latin was the scientific language of the day. So it was through a three-stage process of old Greek writings being transmitted through Arab hands and then translated back into Latin in the Middle Ages that we've ended up with constellations of Greek origin with Latin names and containing stars with Arabic titles like Aldebaran, Betelgeuse and Rigel, as we mentioned a few slides ago. So the Arabs were an important stepping stone in preserving the Greek works and reintroducing them to the West. Well, I said I'd say something about the origin of star names. Well, a lot of these came from Arabic, and a particularly rich source of Arabic star names were the devices called astrolabes, which are a flat representation of the sky used for purposes such as timekeeping. locating celestial objects like a flattened celestial globe. And they're precursors of the planispheres that you might be familiar with. And this one's from the Museum of the History of Science at Oxford, where they've got the world's largest collection of these things. things and a very good website about them as well. And if you've ever seen an astrolabe, you might well have been baffled by all the ornate decorations on them. But all these pointer things over the front do serve a purpose. They're not just for show. And each of them points to the position of a star. And the name of the star is engraved on the pointer, as you might be able to see here. Although in this case, it's all written in Arabic. And in some cases, the pointers were fashioned into little icons to show the position of to show you at a glance what the stars or constellations are that they pointed to. And these two indicate the stars Vega and Altair. Now both Vega and Altair are names which refer to birds, so the pointers are shaped like this. like birds, one sitting with its wings folded and the other one swooping down. While this one at the left is shaped like a horse's head and points to one of the stars of Pegasus, the constellation of the horse. Now some of the star names are completely unfamiliar to us today. This one, also from the Oxford Collection, shows a pointer to a star named Alabor. Now what's Alabor? Well, it was an Arabic name for Sirius, the dog star. and that's why the point is shaped like the head of a dog. Now Geoffrey Chaucer, back in the 14th century, would have recognised this. He was an expert on the astrolabe and he knew this star as Alabor. Well, astronomers eventually reverted... to the original Greek name, Sirius, but for other stars that didn't have Greek names, which, as we've seen, was most of them, the Arabic name survived. So next time you see an astrolabe, amuse yourself by trying to work out which stars are marked on it. So now we've come over 1,000 years since the Almagest was written, and a lot of new star names have been introduced from the Arabs, but as far as the constellations go, we've still got the same 48. that Ptolemy knew. But from here on, things begin to change because of the expansion of astronomical research and also the introduction of printed books and maps, which made it possible to distribute new ideas in large quantity rather than by hand-written manuscripts or individually made celestial globes or astrolabes. Now, what's generally regarded as the first printed celestial chart of any note was drawn by the German artist Albrecht Dürer in 1515 with the help of a couple of astronomers. And it came in two halves, northern and southern, showing all 48 of Ptolemy's constellations. And you can see immediately that the two halves look rather different. The northern half on the left is much busier than the southern half, and that tells us something about where and when these constellations came from, as I'll explain in a moment. Well, if we take a closer look at the northern half, we can see that there are a couple of things that are different about this map from more modern ones. Firstly, the constellation figures are shown back to front as they appear on a celestial globe like the one that the Farnese Atlas is holding. And here's Ursa Major as an example. Now, this was a real design problem for the early mapmakers. People were used to seeing the figures on a globe, so many early maps continue to show them. that way around until eventually the map makers realised it made sense to turn them the right way around as we see them from Earth. And a second difference is that Durer's map has the entire zodiac around the rim as shown by the orange circle here. Now all modern maps have the celestial equator around the rim because they're centred on the celestial pole. You expect to find Polaris at the centre. But Durer drew his chart with the constellations of the zodiac around the rim. and hence Polaris isn't at the centre. I'll circle it for you. It's just above left of centre. Well, that left the southern half of the sky looking rather bare. And there's a second reason the southern sky looks bare. There's a gap around the South Pole where there are no constellations. This orange area here. Now, we've already encountered this. It's the blank area. around the head of the Farnese Atlas. And it's blank because that part of the sky was below the horizon from wherever the constellations were invented. It was too far south. They couldn't see it. And the size of this empty area is an important clue to the latitude at which the people who invented the constellations lived. Now the constellations that the ancient Greeks knew and were shown on Dura's map go down to about 36 degrees from the south celestial pole, which means that the people who invented them must have lived at about latitude 36 degrees north, or, in practice, just a little bit. bit south of that to allow for dimming of stars on the horizon. Now that's too far south for the Greeks, so it seems the Greeks didn't invent the constellations after all. The best guess from various lines of evidence... is that the constellations we know today had their origin around 3,000 years ago in the Middle East among the Sumerians who lived in the area we know as Mesopotamia. And by some unknown means, this knowledge from the Middle East reached the Greeks who incorporated their own myths into it. And the Greek books from the great library at Alexandria were preserved by the Arabs who added some of their own knowledge. And these books were reintroduced into the West. through Arab incursions from North Africa into Spain, and then fanning out into the rest of Europe. So this one slide sums up the six stages and the rather complicated history of the constellations from their origin in the Middle East around 1000 BC up until the end of the 16th century. And it was then, during the age of exploration, as European navigators set out around the globe, that the first new constellations were over 14... hundred years were introduced. From this era there are three leading names, although none of them is particularly well known today. The first is Petrus Plansius, who was a Dutch theologian and cartographer. Plansius is actually the Latin form of his name. In Dutch his name was Plattervoet, which literally means flatfoot. So here he is, Peter Flatfoot. And he's credited with inventing three constellations that we still recognize. today, as listed here. Camelopardalis, the giraffe, Columba, Noah's dove, and Monoceros, the unicorn, all rather odd. And these filled some of the gaps between Ptolemy's Greek constellations. But Plantsius was also interested in filling in that big gap around the south celestial pole. So he instructed a navigator on one of the Dutch voyages of exploration to the East Indies to observe that area for him. And that man... was Peter Dirksen Kaiser. Now, he worked with another crewman, Frederick de Houtman, and there aren't any pictures of Kaiser, but this is supposed to be de Houtman. And they sailed off to the East Indies, and while they were there, they produced a catalogue of southern stars that was divided into 12 new constellations, as listed here. And these constellations mostly depicted fabulous things they had seen on their voyages, such as a peacock, a bird of paradise. a toucan, and a chameleon. And there's still some disagreement over which of them deserves the most credit, but the 12 constellations listed here are now usually attributed jointly to Kaiser and de Houtman. And they first appeared on a celestial globe made by Plantsius in 1598. So these explorers weren't just exploring the unknown parts of the Earth, they were exploring the unknown parts of the sky as well. And for European astronomers, the thrill... of getting the first catalogue of southern stars must have been like we experienced when we got the first pictures of the far side of the moon. It was a part of space that had never been seen before. And to put this into context, this is still before the invention of the telescope. Galileo and his contemporaries didn't turn the first telescopes to the sky until over a decade later. So these are still naked-eye observations. Well, these 12 new southern constellations became better known... five years later in 1603, when they were included in a printed atlas by the German astronomer Johann Bayer. And here's the page from his atlas called Uranometria, the first great printed star atlas that shows these 12 new constellations. Now down at the bottom here, which you probably You can't see very well, but there's a little tableau of Dorado the goldfish following Volans the flying fish. And you might wonder, why is there a goldfish in the sky? But it's not this sort of goldfish that you can see. keep in a bowl, it's this sort. It's the type of fish known as a dolphin fish, which is much bigger and more aggressive. It's also known by its Hawaiian name of mahi-mahi. It's good to eat, they're caught for sport and for eating, and they're really good to eat. they do appear gold, and they chase flying fish. That's one reason flying fish learn to fly, to escape predators such as Dorado. So we see this little tableau of the dolphin fish chasing the flying fish, which is something the early explorers must have seen on their voyages, and they put it in the sky. Well, Bayer's Atlas is significant for another reason, because it featured an innovation that had lasting impact, and that was to label stars with Greek letters. letters. Bayer wasn't actually the first to do this, but he was the most successful, so they're now usually known as Bayer letters. And here's an example in Orion. What Ptolemy described as the bright reddish star on the right shoulder, Bayer labeled as alpha. The star on the other shoulder, he's labeled gamma. Then as we move down, Ptolemy's bright star in the left foot is labeled beta, and the star at the center... of Orion's sword is theta. And Bayer's Greek letters were a great improvement over Ptolemy's long-winded descriptions, and we still use them today. So when astronomers refer to a star as alpha this or beta that, it all goes back to Bayer and this atlas. And even though Beo's Uranometria is 400 years old, it remains one of the most beautiful star atlases ever produced. It's a wonderful combination of engraving, printing, bookbinding, and astronomy, and it's an example of how... great science can also be great art. And that's true of all these old star atlases. In the next few slides, I'll be showing you some examples of constellation pictures from other atlases. Well, later in the 17th century, another group of constellations constellations was introduced by this man, Johann Hevelius. Now he was a Polish astronomer who spent much of his life producing a major star catalogue and atlas, both of which were published in 1690, just after he died. Now he introduced the seven new constellations listed here, and he also suggested three others that weren't adopted. And the frontispiece of the atlas showed Hevelius presenting his constellations to Urania, the muse of astronomy, and an array of greatest astronomers of the past. Now he's in the middle here with a shield in his right hand representing his new constellation of Scutum and in his left hand is a sextant representing sextans and following him in the bottom left corner are the various animals depicted in his new constellations. In the lead is little the Serta, the lizard, then there's the fox and goose, the two hunting dogs, Leo Minor and Lynx. The three snakes at top left represent Cerberus, the three-headed monster that guarded the gates of Hades, but this was one constellation that wasn't adopted, although the others were. Have any of you tried this? Havelius was a brewer by trade. His beer was apparently the favorite of the King of Poland, and after he died, a Havelius beer was produced in his honor. I'm told you can still get it. I've never found it. I've looked in... Quite a number of Polish groceries, but if there are any Poles in the audience, perhaps they can tell me where I can find it. Well, here's one of Hevelius'constellations as shown on his atlas, Vulpecula Cum Ansor, the fox and the goose. Although that's now been shortened to just Volpecula. I suppose the goose was eaten. And Hevelius'atlas still showed constellations back to front as they appear on a globe. So although this is a beautifully engraved atlas, it's not very good for illustrations for books, although some books do use it without actually telling you that the pictures are back to front. And here's another Hevelius invention called Lynx, also from his own atlas. Hevelius was very proud of his eyesight. and he named this Lynx because he said you'd have to be Lynx-eyed to see it because the stars are so faint. I'm not sure if he had ever actually seen a real Lynx. This doesn't look much like one to me. I mentioned Scutum. Here it is. It represents the shield of the King of Poland, Hevelius'patron and a fan of his beer, as we've seen. And this is the only constellation introduced for political reasons that still exists. Well, Hevelius pretty much... much filled in the gaps in the northern sky, but the southern sky still wasn't very well mapped, and the next character in the constellation story set out to rectify that. He was a Frenchman called Nicolas Louis de la Caille. And in 1750, he set out for the Cape of Good Hope in South Africa, where he spent a year making a catalogue of nearly 10,000 stars with a tiny little telescope. It was a huge undertaking, and done in a remarkably short space of time. And in his catalogue he introduced 14 new constellations. And he also divided the existing Greek constellation of Argo, the ship of the Argonauts, into three smaller and more manageable sections, the keel, the stern and the sails. And this is Argo as depicted by Johann Beyer. The ship doesn't have a prow because it was imagined rowing between the clashing rocks at the entrance to the Black Sea, which is what's supposed to be happening here. And even though only part of the ship... was shown in the sky, it was still much larger than any other constellation, which was why Lakai broke it up into three smaller parts. Whereas Kaiser and De Houtman had put exotic animals into the southern sky, Le Caille was much duller and mostly named his constellations after instruments from science and the arts. And as a result, we have some extremely unlikely-sounding constellations, such as an air pump used for experiments on vacuums and air pressure. And these were sophisticated toys for the rich in those days. The Science Museum's got one that George III had. And there's a chemical furnace for... carrying out your chemical experiments. And a pendulum clock. And look at the fantastic amount of detail the engraver has imagined in this part of the sky that consists just of a scattering of very faint stars. This one's a sculptor's studio with a marble head on a table with mallets and a chisel. And these are real constellations, remember. You'll find all of them on a modern star map. Le Caille also introduced Telescopium the Telescope. but it's not the sort of telescope you'd see today. In those days, telescopes had very long tubes to compensate for the fact that their lenses weren't very good and the mountings were pretty cumbersome too. So the type of telescope that Le Caille had in mind was one slung from a tall pole with a pulley and guide ropes to steer it. And here's a real example of a telescope from those days. It looks utterly cumbersome and there's all these people hanging around at the bottom waiting expectantly for... for it to fall over. And at first I didn't notice the man at the top adjusting the pulley. Now he's apparently shinned up the pole on those steps you can see sticking out from the side, which is not something you want to do at night. And I'm not sure how he's going to get down again because there's a couple of blokes at the bottom there making off with a ladder. But looking at this, you can understand why reflecting telescopes of the type used by William Herschel caught on instead of these things. Well, much of Le Caille's original telescopium has now gone as a result of changes to the constellation boundaries. days it's just a rectangular area of sky, and I've outlined its modern borders here in orange. And the top of the pole has been cut off, and so has the upper end of the tube, which used to go off to the upper right there. And the illustrations on these past few few slides come from what I think is the greatest star atlas ever made. It was called Uranographia, not to be confused with Bayer's earlier Uranometria, and its author was a German astronomer called Johann Bode, who's probably best known for his association with Bode's law. He had eye trouble from an early age, apparently, particularly with his right eye, and pictures always show him squinting. But nevertheless, he became very adept at mathematics and astronomy, and his great star atlas is generally... reckoned to have been the pinnacle of the celestial mapmaker's art. Bode's Atlas was published in 1801. It contains around 100 constellations, plenty more than we have today, and so it's a good place to find illustrations of many figures that have since been dropped from astronomers'charts. In fact, during the 18th century, inventing new constellations became a bit of a sport among astronomers, and there were some quite nice ideas. For example... Bode himself invented one called Officina Typographica, the printing shop commemorating Gutenberg's invention of printing. Then there was Globus Aerostaticus, the Montgolfier balloon floating serenely through the sky. Felis the cat. I'm rather sorry this one didn't make it, although it's a pretty grumpy looking cat. And Machina Electrica, the electrostatic generator. Thank you And for a while, there was even a second telescope in the sky. This one was called Herschel's telescope, and it depicted the reflector with which William Herschel discovered the planet Uranus from his back garden in Bath in 1781. And here it is, shown on Bode's atlas just 20 years after the discovery. And here's one constellation that came closer than most to making the final list. It's Antinoas, who was a real person. He was the teenage boyfriend of the... the Emperor Hadrian. And the story is that he drowned in the Nile during a boat trip in AD 130. Hadrian was heartbroken and wanted him commemorated among the stars. And Ptolemy included Antinous in the Almagest as a subdivision of the constellation Aquila the Eagle, which is how he's shown here. Now remember that Ptolemy worked at Alexandria at the mouth of the Nile and he compiled the Almagest about 20 years after the famous drowning. So he would have known the story. so Antinous was what you might call a gay icon and you can find him on star charts right through to the Victorian era when perhaps they weren't so keen on gay icons so you see we could have had some quite fascinating additional constellations but in fact nothing suggested after Lecaille's 14 new southern constellations in the 1750s was ever adopted but even into the 20th century though there still wasn't an an officially recognized list of constellations or their names. If you look at various maps made 100 years ago, you'll find that the choice of constellations or their names or spellings can vary from map to map. So rationalizing all this was one of the first things that the International Astronomical Union did when it came into being about 90 years ago. And the International Astronomical Union, or the IAU, is astronomy's governing body, and it was one of the first international... scientific unions to be set up. At its first meeting in 1922, the IAU adopted a list of the 88 constellations that we know today, along with official names for each. And these were constellations that, by common consent, were widely used in the major star catalogues of the day, and there wasn't any huge disagreement about the final choice, unlike the recent controversy about whether Pluto is a planet, for example. However, although that decision fixed the number of constellations, there still weren't any official boundaries. And until then, the constellation boundaries had been shown simply as snaking lines between the various figures. Here's the constellation of Auriga the charioteer as an example. And these boundary lines varied from map to map, so faint stars could be in different constellations depending which map you were looking at. And what's more, some constellations overlapped, and some stars were actually in the same place. actually shared between constellations. In the case of the charioteer here, the star on his right foot is also the star at the tip of the horn of Taurus the bull. And you can see this a bit more clearly as we zoom in. So the same star could be part of the bull or part of the charioteer depending which constellation you were looking at. So properly defined boundaries were needed, but how do you draw a boundary in the sky? There aren't any natural features we can use like on Earth, no coastlines or rivers or mountain ranges, for example. So they decided to divide up the sky along coordinate lines using the equivalent of latitude and longitude on Earth. And the job of this was entrusted to a Belgian at the Royal Observatory in Brussels called Eugene Del Porte. And in 1930, he presented his results in an atlas showing the borders of the constellations against the stars. And this is one of the charts from his atlas, and you can see the borders zigzagging along the grid lines. And I've highlighted the border of Cassiopeia in orange to make it clearer. Now one particularly knotty problem Delport faced was this chap entwined by a snake. He's called Ophiuchus, who was the god of medicine, and the snake is the symbol of healing. Now they form a very nice tableau, but how do you divide them? them into separate constellations. Well, what Delport actually did was to chop the snake into two halves. And as you can see on this modern map, you now have its head on one side of a fucus and its tail on the other. But they're both parts of the same constellation, Serpens. And this is unique in the sky. It's the only example of a constellation divided into two, but it still only counts as one constellation. Well, Delport's atlas amounts to an international treaty on the demarcation of the sky, something which everyone adheres to without question. Every star is now unambiguously allocated to a specific constellation, and there are no... border disputes unlike on Earth. Incidentally, if you're wondering what happened to that star shared between the charioteer and the bull, well, the bull got it. The bull kept the tip of his horn, but the charioteer lost his foot. But you'll notice that there's no sign of the beautiful constellation pictures on Delport's map because by that time they had fallen out of use. Astronomers had dropped them as being too frivolous. Nowadays, when astronomers say that something is in a given constellation, they mean simply that it's in that area of sky, rather than forming part of a picture. However, without the old constellation pictures, star charts become a rather confusing mass of dots, as here. So now you'll find that the main stars in the sky are the stars in the sky, and the stars in the sky are the stars in the sky. in each constellation are very often joined up to help you recognize their overall shape. And here's a typical example I picked up off the internet. These linking lines have no official status at all, and they vary from map to map, but they're helpful in identifying the major patterns. Now one final thought for you is that the old constellation patterns won't last forever. As you may know, all stars are moving through space, so they're changing their positions as seen from Earth very slowly. These are called their proper motions. And you don't notice any difference over a human lifetime, but over tens or hundreds of thousands of years, the shapes of constellations will change quite noticeably, so they'll become almost unrecognizable. And I've got three examples. examples for you here. Firstly, here's the plough as it appears today. And this is as it will appear in 100,000 years time. You'll notice that the stars at each end don't change much, but the five in the middle do. And they're part of a group called the Ursa Major Moving Cluster. I'll show you that again, but leaving the current shape of the plough for comparison. So the handle becomes much more bent, but the bowl flattens out. And here's the familiar cross shape of Cygnus, the swan, as it appears today. And this is it, 100,000 years from now. What do you think that looks like? Deneb and Alboreo don't change much, but there are big differences in the wings. Here it is again, keeping the current shape for comparison. You'll notice that the one on the left, Epsilon, really shoots off and completely disrupts the shape. And finally, here are the stars of Leo, forming the familiar shape of the crouching lion. And these go all over the place. Even so, you might still be able to imagine something like a crouching lion out of the final result. And I'll show you that again. See, Regulus stays pretty much where it is, but look at how far Gamma Leonis travels. It goes right across the constellation, so you'll need a pretty good imagination to make something out of that lot. And as well as those changes in shape, some stars... will actually change constellations altogether. They'll move over the boundaries, out of their existing constellations and into their neighbours. So what's going to happen to our stellar nomenclature when that happens? Well, fortunately that's not something that we need worry about. Those are problems. for far in the future. And just to finish off, you may know that there are companies that offer to name stars after someone you know or want to commemorate. And from time to time, organisations such as the Royal Astronomical Society get enquiries about buying star names. Now, I'm sorry to have to tell you that such schemes have no official validity whatsoever. They're simply a novelty. So if you want something to hang on the bathroom wall, that's fine, but don't expect astronomers to take it seriously. and you can see here what the International Astronomical Union has to say about the matter and that's the view of the Royal Astronomical Society as well well I hope I've been able to show you that the constellations aren't just about the stars they're also about poetry and art and above all human imagination And they give us a very real connection with the earliest human civilizations who looked up and imagined those first pictures in the sky. And finally, you can find the stories and histories of all the constellations, and some of the obsolete ones as well, on my website, and I've given you the address here. And I'll hand it back to you, Felicity, as my voice gives out. Thank you.

back again and you'll realise that we've had some refurbishment work done in this room. We've got our nice new screen so it will no longer be difficult for you to see the pictures at the front and we've got... some cooling put in and so hopefully it's a new and improved experience.

So it's my very happy duty today to introduce to you our first speaker in our new autumn series of lunchtime lectures and today we have Mr Ian Ridpath. Ian got interested in astronomy at an early age like probably many other people through watching. Patrick Moore and so he's been hooked ever since and he's lucky enough to be able to write popular books about astronomy and he tells me that he's written a book about this very topic that he's speaking about today which is called Star Tales and he's also the editor of the Oxford Dictionary of Astronomy as well so if you need to look anything up then I highly recommend that volume.

But that's enough from me, and so I'd like to welcome Ian to the podium to speak about pictures in the sky, the origin and history of the constellations. Thank you. Okay, well, good afternoon, everybody. It's nice to see there's a good turnout.

Thank you all for giving up your lunch times. Well, the constellations are something that we pretty much take for granted, aren't they? I mean, we tend to assume that they've always been there.

there like the stars themselves. But in fact they haven't because they are a product of human imagination. They're in fact one of the earliest attempts to impart some form of...

order on the universe around us. And being a human invention, there's a story, like all human inventions, about how they came to be. And that's the story that I'm going to tell you today.

And it's a story that goes back over 3,000 years. And it involves a trail of many thousands of miles around the Mediterranean as we follow the route by which the ancient constellations were handed down to us. And along the way, I'll introduce you to a story that goes back over 3,000 years.

you to some more recent astronomers and explorers who added their own constellations to the originals, and we'll meet some other constellations that didn't make the final selection. And at the end, I'll direct you to a website which will tell you more about what I've been saying, so if you get lost, don't worry. Well, today there are 88 constellations recognized in all, and if we can have the lights down, please.

And they fit together like pieces of a jigsaw to... Not that much, I can't see my nose. Thank you.

And they fit together like pieces of a jigsaw to fill the entire sky from the north celestial pole to the south. And their names and their boundaries are now fixed by international agreement, so you can't just add new constellations or change their shape. and sizes to suit yourself, but it's only been like that within the past century. Originally, constellations were simply regarded as imaginary pictures without rigid boundaries, sometimes even overlapping each other and sharing the same image. the same stars.

And I'm going to try to explain how we ended up with these 88 constellations and who decided on the boundaries, and along the way I'll explain how the names of certain stars came about as well. Well, let's start our journey by turning the clock back and imagining the scene in a village thousands of years ago. The villagers are gathered around a communal fire. Dinner is over and the fire is dying down. one of the village elders begins to tell stories.

And these are stories that have been handed down through generations by word of mouth, which is how stories were transmitted in the days before writing. And the stories are about gods, mythical heroes, fabulous beasts. There's a story about a beautiful princess saved by a dashing hero.

A lecherous god who turns himself into animals to abduct beautiful girls and boys. And a giant hunter who was stung to death by a scorpion. And to illustrate these tales, the storyteller uses the stars. And I think this is how the first constellations came into being.

The sky was like a great projection screen. and the audience were invited to imagine the characters in the various tales among the stars, like a picture book in the sky. So I think that in most cases, the stories came first, and patterns in the sky were visualized to fit.

those stories. And in a lot of cases, it was quite an unconvincing force fit. And this explains why many of the constellations really don't look anything like what they're supposed to represent, which of course is something that always battles newcomers.

Mind you, some of the constellation shapes are quite a good fit. You might well see a lion in the stars of Leo, and a scorpion in the stars of Scorpius. But I don't think anyone has ever tried to argue that you can see a goat with a tail like a fish among the stars of Capricornus, or that Cassiopeia looks very much like a woman sitting in a chair and combing her hair. So I think it's important to realize that the original constellations weren't intended to be taken as literal representations. They were simply allegorical.

Well, the constellations that everyone uses today have come down to us. from the Greeks, although of course other cultures imagined completely different pictures in the sky. The Chinese, for example, had over three times as many constellations as we do, mostly quite small, and they don't look anything like the constellations that we know. Well here's part of a chart that was found at a place called Dunhuang on the Silk Road in China, and it shows the Chinese constellations around the north pole of the sky, dating from about the same era as the ancient Greeks. Greek astronomer Ptolemy.

Now you should be able to make out the familiar shape of the plough. Can you see it down there at the bottom? But even an experienced astronomer would be hard-pressed to recognize much else.

Now this is in fact a fantastically interesting document. It's over 1300 years old and it's the oldest surviving star chart drawn on paper because of course the Chinese also invented paper. And it's in the British Library and if you want to find out more about about it, go onto their website and they've got loads more about it there. But for this talk I'm not going to say any more about Chinese constellations, I'll be concentrating just on the Western tradition. Now one thing we now know that the ancient sky watchers didn't is that the stars in a constellation have no physical connection with each other.

Up until only a few centuries ago it was thought that stars were like lights stuck on an invisible sphere surrounding the Earth. But thanks to modern science, we know that stars are glowing balls of gas, like the sun, and they're all at different distances from us, so far away that their light takes many years or even centuries to reach us. And the patterns they form are purely a matter of chance, like the W shape of Cassiopeia here.

Well, in Greek literature, the first mention of constellations dates back to about 700 BC in the works of Homer and Hesiod, although they mentioned only a handful of constellations and stars, such as the Great Bear, Orion, the Pleiades star cluster, I mean, at that time, the Pleiades was regarded as a separate constellation in its own right, and the dog star Sirius. It's not until about 350 BC that there is evidence for a reasonably full set of Greek constellations, and that comes from an astronomer called Eudoxus. Now, his original writings are lost, but another Greek called Aratus turned them into a poem called The Phenomena around 275 BC, and that does still exist. And in this poem, Aratus gave us a complete guide to the constellations known to the ancient Greeks.

Well, unfortunately, the poem's a bit difficult to follow in places. Here's an example. example describing the bears and Draco the dragon around the North Celestial Pole.

I know it doesn't look much like a poem, but presumably it rhymed a bit better in the original Greek. If there's anyone here who can speak Greek, perhaps they can tell me afterwards. Well, we can get our first look at pictures of the ancient Greek constellations described by Aratus on this sculpture of Atlas. Now, he's not holding up the earth, as we might normally think, but it's the heavens.

And what he's holding here is actually the... oldest known celestial globe. And the statue is called the Farnese Atlas because it was bought by an Italian cardinal called Farnese.

And it's thought to be a Roman copy of an older Greek original showing the same constellations as Aratus described in his poem. And in this close-up you might be able to see the sinuous shape of Hydra the water snake, which is actually the largest constellation in the sky, with Crater the Cup and Corvus Corvus. the crow on its back.

And the crow, the cup, and the water snake are linked in a tale from Greek myth. And below left of it is Argo, the ship of the Argonauts, which of course features in a major epic from Greek myth. And to the right of that is Centaurus, who represents Chiron, the wise centaur. And of course, being a globe, everything is back to front by comparison with the way we see it from Earth.

And to see everything the right way round, you would have to go back and forth between the two. would have to be inside the globe. And in the area around Atlas's head, there aren't any constellations at all, because that's the area around the South Pole that couldn't be seen from the Mediterranean.

So the figures on this globe are pictures in the sky the way the ancient Greek people would have imagined them. Well, the first truly scientific description of the ancient Greek constellations comes from an encyclopedia of astronomy and mathematics called the Almagest, which is one of the great books of antiquity. And it was written around A.D.

1100. 150 by Ptolemy, who's usually regarded as a Greek scientist, although he worked at Alexandria in northern Egypt, near the mouth of the Nile, rather than in Greece itself. And the Almagest contained a catalogue of about about a thousand stars divided into 48 constellations. And it's generally thought that it's based on a catalogue compiled by an earlier Greek called Hipparchus, which hasn't survived. Ptolemy's original manuscript hasn't survived either, but it was laboriously copied and recopied by hand, and we still have some of those copies. And with the invention of printing in the 15th century, it was possible to make many copies quite quickly.

And here's a page from the first. printed edition of the Almagest from 1515. And the columns on the right have got the coordinates and the brightness of the star, but what seems odd to us now is this section on the left where each star is identified by a long-winded description of its position in the overall constellation shape. Now these days we'd give each star a catalogue number, but Ptolemy didn't do that because he still regarded the constellations as real pictures. For example, this description of a star in Taurus, the reddish one on the southern eye. That's what Ptolemy called the star we know as Aldebaran.

But Aldebaran is an Arabic name that came later. Here's another one, this time in Orion. The bright reddish star on the right shoulder.

We now call that Betelgeuse. Or the bright star in the left foot. That's Rigel, also in Orion.

But again, the Greeks didn't have a name. name for it. And I find it amazing that three of the brightest and most prominent stars in the sky didn't have names in Greek times, or at least if they did, they weren't mentioned by Ptolemy.

For some reason, the Greeks weren't particularly interested in naming individual stars. Well, Ptolemy was the last of the ancient Greek astronomers, and after him there's a long gap during which the center of astronomy moved away from Greece into the Middle East, and it's at this stage that the Arabs come into the story. highlight from this era is provided by a Persian astronomer called Al-Sufi, or Azofi in its Latinized form. And Al-Sufi's masterwork was called The Book of the Fixed Stars, which was a revised and updated version.

of Ptolemy's Almagest. And even though it was published 800 years after the Almagest, it contained the same constellations as the Greeks knew. But Al-Sufi added rather nice illustrations of each constellation, and of course they weren't done in Greek style, but Islamic style. And here you can see Orion in his Islamic dress, what the Greeks imagined as his shield has become a long sleeve. And Al-Sufi's book showed each constellation in two ways.

one as it's seen from the earth on the left there and the other one as seen on a celestial globe where it appears back to front. And since this was still in the days before printing all books were in manuscript form so they had to be copied individually by hand and the illustrations were different in each manuscript. And this picture is actually from a copy made in the 13th century 300 years after the book was first written.

Now to stop and put this into context, we're in the Middle Ages in Europe and by this time the Arab Empire has expanded through North Africa and into Spain and it was through this route of the Arabs coming into Spain that the ancient Greek works were reintroduced into Western Europe from the 11th century onwards. And the Spanish city of Toledo in particular is said to have become a veritable translation factory during the 12th century, and scholars flopped there from all over Western Europe. to study the marvellous new works, not just on astronomy, but mathematics and all other branches of science. And the most prolific of these translators was Gerard of Cremona, an Italian who went to Toledo in his late twenties, specifically to study the Almagest, and ended up spending the rest of his life there, translating over 70 different works of all kinds. And it was Gerard's Latin translation of the Almagest that formed the basis for the first printed edition, which I share with you.

showed you a couple of slides ago. And the language that Gerard and his colleagues translated the Arabic manuscripts into wasn't Spanish or English, but Latin, because of course Latin was the scientific language of the day. So it was through a three-stage process of old Greek writings being transmitted through Arab hands and then translated back into Latin in the Middle Ages that we've ended up with constellations of Greek origin with Latin names and containing stars with Arabic titles like Aldebaran, Betelgeuse and Rigel, as we mentioned a few slides ago. So the Arabs were an important stepping stone in preserving the Greek works and reintroducing them to the West. Well, I said I'd say something about the origin of star names.

Well, a lot of these came from Arabic, and a particularly rich source of Arabic star names were the devices called astrolabes, which are a flat representation of the sky used for purposes such as timekeeping. locating celestial objects like a flattened celestial globe. And they're precursors of the planispheres that you might be familiar with.

And this one's from the Museum of the History of Science at Oxford, where they've got the world's largest collection of these things. things and a very good website about them as well. And if you've ever seen an astrolabe, you might well have been baffled by all the ornate decorations on them.

But all these pointer things over the front do serve a purpose. They're not just for show. And each of them points to the position of a star.

And the name of the star is engraved on the pointer, as you might be able to see here. Although in this case, it's all written in Arabic. And in some cases, the pointers were fashioned into little icons to show the position of to show you at a glance what the stars or constellations are that they pointed to.

And these two indicate the stars Vega and Altair. Now both Vega and Altair are names which refer to birds, so the pointers are shaped like this. like birds, one sitting with its wings folded and the other one swooping down.

While this one at the left is shaped like a horse's head and points to one of the stars of Pegasus, the constellation of the horse. Now some of the star names are completely unfamiliar to us today. This one, also from the Oxford Collection, shows a pointer to a star named Alabor. Now what's Alabor?

Well, it was an Arabic name for Sirius, the dog star. and that's why the point is shaped like the head of a dog. Now Geoffrey Chaucer, back in the 14th century, would have recognised this. He was an expert on the astrolabe and he knew this star as Alabor. Well, astronomers eventually reverted...

to the original Greek name, Sirius, but for other stars that didn't have Greek names, which, as we've seen, was most of them, the Arabic name survived. So next time you see an astrolabe, amuse yourself by trying to work out which stars are marked on it. So now we've come over 1,000 years since the Almagest was written, and a lot of new star names have been introduced from the Arabs, but as far as the constellations go, we've still got the same 48. that Ptolemy knew. But from here on, things begin to change because of the expansion of astronomical research and also the introduction of printed books and maps, which made it possible to distribute new ideas in large quantity rather than by hand-written manuscripts or individually made celestial globes or astrolabes. Now, what's generally regarded as the first printed celestial chart of any note was drawn by the German artist Albrecht Dürer in 1515 with the help of a couple of astronomers.

And it came in two halves, northern and southern, showing all 48 of Ptolemy's constellations. And you can see immediately that the two halves look rather different. The northern half on the left is much busier than the southern half, and that tells us something about where and when these constellations came from, as I'll explain in a moment.

Well, if we take a closer look at the northern half, we can see that there are a couple of things that are different about this map from more modern ones. Firstly, the constellation figures are shown back to front as they appear on a celestial globe like the one that the Farnese Atlas is holding. And here's Ursa Major as an example. Now, this was a real design problem for the early mapmakers. People were used to seeing the figures on a globe, so many early maps continue to show them.

that way around until eventually the map makers realised it made sense to turn them the right way around as we see them from Earth. And a second difference is that Durer's map has the entire zodiac around the rim as shown by the orange circle here. Now all modern maps have the celestial equator around the rim because they're centred on the celestial pole.

You expect to find Polaris at the centre. But Durer drew his chart with the constellations of the zodiac around the rim. and hence Polaris isn't at the centre. I'll circle it for you. It's just above left of centre.

Well, that left the southern half of the sky looking rather bare. And there's a second reason the southern sky looks bare. There's a gap around the South Pole where there are no constellations.

This orange area here. Now, we've already encountered this. It's the blank area. around the head of the Farnese Atlas. And it's blank because that part of the sky was below the horizon from wherever the constellations were invented.

It was too far south. They couldn't see it. And the size of this empty area is an important clue to the latitude at which the people who invented the constellations lived.

Now the constellations that the ancient Greeks knew and were shown on Dura's map go down to about 36 degrees from the south celestial pole, which means that the people who invented them must have lived at about latitude 36 degrees north, or, in practice, just a little bit. bit south of that to allow for dimming of stars on the horizon. Now that's too far south for the Greeks, so it seems the Greeks didn't invent the constellations after all.

The best guess from various lines of evidence... is that the constellations we know today had their origin around 3,000 years ago in the Middle East among the Sumerians who lived in the area we know as Mesopotamia. And by some unknown means, this knowledge from the Middle East reached the Greeks who incorporated their own myths into it.

And the Greek books from the great library at Alexandria were preserved by the Arabs who added some of their own knowledge. And these books were reintroduced into the West. through Arab incursions from North Africa into Spain, and then fanning out into the rest of Europe. So this one slide sums up the six stages and the rather complicated history of the constellations from their origin in the Middle East around 1000 BC up until the end of the 16th century.

And it was then, during the age of exploration, as European navigators set out around the globe, that the first new constellations were over 14... hundred years were introduced. From this era there are three leading names, although none of them is particularly well known today.

The first is Petrus Plansius, who was a Dutch theologian and cartographer. Plansius is actually the Latin form of his name. In Dutch his name was Plattervoet, which literally means flatfoot.

So here he is, Peter Flatfoot. And he's credited with inventing three constellations that we still recognize. today, as listed here. Camelopardalis, the giraffe, Columba, Noah's dove, and Monoceros, the unicorn, all rather odd.

And these filled some of the gaps between Ptolemy's Greek constellations. But Plantsius was also interested in filling in that big gap around the south celestial pole. So he instructed a navigator on one of the Dutch voyages of exploration to the East Indies to observe that area for him. And that man...

was Peter Dirksen Kaiser. Now, he worked with another crewman, Frederick de Houtman, and there aren't any pictures of Kaiser, but this is supposed to be de Houtman. And they sailed off to the East Indies, and while they were there, they produced a catalogue of southern stars that was divided into 12 new constellations, as listed here.

And these constellations mostly depicted fabulous things they had seen on their voyages, such as a peacock, a bird of paradise. a toucan, and a chameleon. And there's still some disagreement over which of them deserves the most credit, but the 12 constellations listed here are now usually attributed jointly to Kaiser and de Houtman. And they first appeared on a celestial globe made by Plantsius in 1598. So these explorers weren't just exploring the unknown parts of the Earth, they were exploring the unknown parts of the sky as well. And for European astronomers, the thrill...

of getting the first catalogue of southern stars must have been like we experienced when we got the first pictures of the far side of the moon. It was a part of space that had never been seen before. And to put this into context, this is still before the invention of the telescope. Galileo and his contemporaries didn't turn the first telescopes to the sky until over a decade later.

So these are still naked-eye observations. Well, these 12 new southern constellations became better known... five years later in 1603, when they were included in a printed atlas by the German astronomer Johann Bayer. And here's the page from his atlas called Uranometria, the first great printed star atlas that shows these 12 new constellations. Now down at the bottom here, which you probably You can't see very well, but there's a little tableau of Dorado the goldfish following Volans the flying fish.

And you might wonder, why is there a goldfish in the sky? But it's not this sort of goldfish that you can see. keep in a bowl, it's this sort.

It's the type of fish known as a dolphin fish, which is much bigger and more aggressive. It's also known by its Hawaiian name of mahi-mahi. It's good to eat, they're caught for sport and for eating, and they're really good to eat. they do appear gold, and they chase flying fish. That's one reason flying fish learn to fly, to escape predators such as Dorado.

So we see this little tableau of the dolphin fish chasing the flying fish, which is something the early explorers must have seen on their voyages, and they put it in the sky. Well, Bayer's Atlas is significant for another reason, because it featured an innovation that had lasting impact, and that was to label stars with Greek letters. letters. Bayer wasn't actually the first to do this, but he was the most successful, so they're now usually known as Bayer letters. And here's an example in Orion.

What Ptolemy described as the bright reddish star on the right shoulder, Bayer labeled as alpha. The star on the other shoulder, he's labeled gamma. Then as we move down, Ptolemy's bright star in the left foot is labeled beta, and the star at the center...

of Orion's sword is theta. And Bayer's Greek letters were a great improvement over Ptolemy's long-winded descriptions, and we still use them today. So when astronomers refer to a star as alpha this or beta that, it all goes back to Bayer and this atlas. And even though Beo's Uranometria is 400 years old, it remains one of the most beautiful star atlases ever produced.

It's a wonderful combination of engraving, printing, bookbinding, and astronomy, and it's an example of how... great science can also be great art. And that's true of all these old star atlases. In the next few slides, I'll be showing you some examples of constellation pictures from other atlases.

Well, later in the 17th century, another group of constellations constellations was introduced by this man, Johann Hevelius. Now he was a Polish astronomer who spent much of his life producing a major star catalogue and atlas, both of which were published in 1690, just after he died. Now he introduced the seven new constellations listed here, and he also suggested three others that weren't adopted. And the frontispiece of the atlas showed Hevelius presenting his constellations to Urania, the muse of astronomy, and an array of greatest astronomers of the past.

Now he's in the middle here with a shield in his right hand representing his new constellation of Scutum and in his left hand is a sextant representing sextans and following him in the bottom left corner are the various animals depicted in his new constellations. In the lead is little the Serta, the lizard, then there's the fox and goose, the two hunting dogs, Leo Minor and Lynx. The three snakes at top left represent Cerberus, the three-headed monster that guarded the gates of Hades, but this was one constellation that wasn't adopted, although the others were. Have any of you tried this?

Havelius was a brewer by trade. His beer was apparently the favorite of the King of Poland, and after he died, a Havelius beer was produced in his honor. I'm told you can still get it. I've never found it. I've looked in...

Quite a number of Polish groceries, but if there are any Poles in the audience, perhaps they can tell me where I can find it. Well, here's one of Hevelius'constellations as shown on his atlas, Vulpecula Cum Ansor, the fox and the goose. Although that's now been shortened to just Volpecula.

I suppose the goose was eaten. And Hevelius'atlas still showed constellations back to front as they appear on a globe. So although this is a beautifully engraved atlas, it's not very good for illustrations for books, although some books do use it without actually telling you that the pictures are back to front. And here's another Hevelius invention called Lynx, also from his own atlas. Hevelius was very proud of his eyesight.

and he named this Lynx because he said you'd have to be Lynx-eyed to see it because the stars are so faint. I'm not sure if he had ever actually seen a real Lynx. This doesn't look much like one to me. I mentioned Scutum.

Here it is. It represents the shield of the King of Poland, Hevelius'patron and a fan of his beer, as we've seen. And this is the only constellation introduced for political reasons that still exists.

Well, Hevelius pretty much... much filled in the gaps in the northern sky, but the southern sky still wasn't very well mapped, and the next character in the constellation story set out to rectify that. He was a Frenchman called Nicolas Louis de la Caille. And in 1750, he set out for the Cape of Good Hope in South Africa, where he spent a year making a catalogue of nearly 10,000 stars with a tiny little telescope. It was a huge undertaking, and done in a remarkably short space of time.

And in his catalogue he introduced 14 new constellations. And he also divided the existing Greek constellation of Argo, the ship of the Argonauts, into three smaller and more manageable sections, the keel, the stern and the sails. And this is Argo as depicted by Johann Beyer. The ship doesn't have a prow because it was imagined rowing between the clashing rocks at the entrance to the Black Sea, which is what's supposed to be happening here. And even though only part of the ship...

was shown in the sky, it was still much larger than any other constellation, which was why Lakai broke it up into three smaller parts. Whereas Kaiser and De Houtman had put exotic animals into the southern sky, Le Caille was much duller and mostly named his constellations after instruments from science and the arts. And as a result, we have some extremely unlikely-sounding constellations, such as an air pump used for experiments on vacuums and air pressure.

And these were sophisticated toys for the rich in those days. The Science Museum's got one that George III had. And there's a chemical furnace for...

carrying out your chemical experiments. And a pendulum clock. And look at the fantastic amount of detail the engraver has imagined in this part of the sky that consists just of a scattering of very faint stars. This one's a sculptor's studio with a marble head on a table with mallets and a chisel. And these are real constellations, remember.

You'll find all of them on a modern star map. Le Caille also introduced Telescopium the Telescope. but it's not the sort of telescope you'd see today.

In those days, telescopes had very long tubes to compensate for the fact that their lenses weren't very good and the mountings were pretty cumbersome too. So the type of telescope that Le Caille had in mind was one slung from a tall pole with a pulley and guide ropes to steer it. And here's a real example of a telescope from those days. It looks utterly cumbersome and there's all these people hanging around at the bottom waiting expectantly for...

for it to fall over. And at first I didn't notice the man at the top adjusting the pulley. Now he's apparently shinned up the pole on those steps you can see sticking out from the side, which is not something you want to do at night. And I'm not sure how he's going to get down again because there's a couple of blokes at the bottom there making off with a ladder.

But looking at this, you can understand why reflecting telescopes of the type used by William Herschel caught on instead of these things. Well, much of Le Caille's original telescopium has now gone as a result of changes to the constellation boundaries. days it's just a rectangular area of sky, and I've outlined its modern borders here in orange. And the top of the pole has been cut off, and so has the upper end of the tube, which used to go off to the upper right there. And the illustrations on these past few few slides come from what I think is the greatest star atlas ever made.

It was called Uranographia, not to be confused with Bayer's earlier Uranometria, and its author was a German astronomer called Johann Bode, who's probably best known for his association with Bode's law. He had eye trouble from an early age, apparently, particularly with his right eye, and pictures always show him squinting. But nevertheless, he became very adept at mathematics and astronomy, and his great star atlas is generally...

reckoned to have been the pinnacle of the celestial mapmaker's art. Bode's Atlas was published in 1801. It contains around 100 constellations, plenty more than we have today, and so it's a good place to find illustrations of many figures that have since been dropped from astronomers'charts. In fact, during the 18th century, inventing new constellations became a bit of a sport among astronomers, and there were some quite nice ideas. For example... Bode himself invented one called Officina Typographica, the printing shop commemorating Gutenberg's invention of printing.

Then there was Globus Aerostaticus, the Montgolfier balloon floating serenely through the sky. Felis the cat. I'm rather sorry this one didn't make it, although it's a pretty grumpy looking cat.

And Machina Electrica, the electrostatic generator. Thank you And for a while, there was even a second telescope in the sky. This one was called Herschel's telescope, and it depicted the reflector with which William Herschel discovered the planet Uranus from his back garden in Bath in 1781. And here it is, shown on Bode's atlas just 20 years after the discovery.

And here's one constellation that came closer than most to making the final list. It's Antinoas, who was a real person. He was the teenage boyfriend of the...

the Emperor Hadrian. And the story is that he drowned in the Nile during a boat trip in AD 130. Hadrian was heartbroken and wanted him commemorated among the stars. And Ptolemy included Antinous in the Almagest as a subdivision of the constellation Aquila the Eagle, which is how he's shown here.

Now remember that Ptolemy worked at Alexandria at the mouth of the Nile and he compiled the Almagest about 20 years after the famous drowning. So he would have known the story. so Antinous was what you might call a gay icon and you can find him on star charts right through to the Victorian era when perhaps they weren't so keen on gay icons so you see we could have had some quite fascinating additional constellations but in fact nothing suggested after Lecaille's 14 new southern constellations in the 1750s was ever adopted but even into the 20th century though there still wasn't an an officially recognized list of constellations or their names. If you look at various maps made 100 years ago, you'll find that the choice of constellations or their names or spellings can vary from map to map. So rationalizing all this was one of the first things that the International Astronomical Union did when it came into being about 90 years ago.

And the International Astronomical Union, or the IAU, is astronomy's governing body, and it was one of the first international... scientific unions to be set up. At its first meeting in 1922, the IAU adopted a list of the 88 constellations that we know today, along with official names for each. And these were constellations that, by common consent, were widely used in the major star catalogues of the day, and there wasn't any huge disagreement about the final choice, unlike the recent controversy about whether Pluto is a planet, for example. However, although that decision fixed the number of constellations, there still weren't any official boundaries.

And until then, the constellation boundaries had been shown simply as snaking lines between the various figures. Here's the constellation of Auriga the charioteer as an example. And these boundary lines varied from map to map, so faint stars could be in different constellations depending which map you were looking at. And what's more, some constellations overlapped, and some stars were actually in the same place. actually shared between constellations.

In the case of the charioteer here, the star on his right foot is also the star at the tip of the horn of Taurus the bull. And you can see this a bit more clearly as we zoom in. So the same star could be part of the bull or part of the charioteer depending which constellation you were looking at.

So properly defined boundaries were needed, but how do you draw a boundary in the sky? There aren't any natural features we can use like on Earth, no coastlines or rivers or mountain ranges, for example. So they decided to divide up the sky along coordinate lines using the equivalent of latitude and longitude on Earth. And the job of this was entrusted to a Belgian at the Royal Observatory in Brussels called Eugene Del Porte. And in 1930, he presented his results in an atlas showing the borders of the constellations against the stars.

And this is one of the charts from his atlas, and you can see the borders zigzagging along the grid lines. And I've highlighted the border of Cassiopeia in orange to make it clearer. Now one particularly knotty problem Delport faced was this chap entwined by a snake. He's called Ophiuchus, who was the god of medicine, and the snake is the symbol of healing.

Now they form a very nice tableau, but how do you divide them? them into separate constellations. Well, what Delport actually did was to chop the snake into two halves.

And as you can see on this modern map, you now have its head on one side of a fucus and its tail on the other. But they're both parts of the same constellation, Serpens. And this is unique in the sky. It's the only example of a constellation divided into two, but it still only counts as one constellation. Well, Delport's atlas amounts to an international treaty on the demarcation of the sky, something which everyone adheres to without question.

Every star is now unambiguously allocated to a specific constellation, and there are no... border disputes unlike on Earth. Incidentally, if you're wondering what happened to that star shared between the charioteer and the bull, well, the bull got it. The bull kept the tip of his horn, but the charioteer lost his foot.

But you'll notice that there's no sign of the beautiful constellation pictures on Delport's map because by that time they had fallen out of use. Astronomers had dropped them as being too frivolous. Nowadays, when astronomers say that something is in a given constellation, they mean simply that it's in that area of sky, rather than forming part of a picture.

However, without the old constellation pictures, star charts become a rather confusing mass of dots, as here. So now you'll find that the main stars in the sky are the stars in the sky, and the stars in the sky are the stars in the sky. in each constellation are very often joined up to help you recognize their overall shape. And here's a typical example I picked up off the internet.

These linking lines have no official status at all, and they vary from map to map, but they're helpful in identifying the major patterns. Now one final thought for you is that the old constellation patterns won't last forever. As you may know, all stars are moving through space, so they're changing their positions as seen from Earth very slowly.

These are called their proper motions. And you don't notice any difference over a human lifetime, but over tens or hundreds of thousands of years, the shapes of constellations will change quite noticeably, so they'll become almost unrecognizable. And I've got three examples.

examples for you here. Firstly, here's the plough as it appears today. And this is as it will appear in 100,000 years time. You'll notice that the stars at each end don't change much, but the five in the middle do. And they're part of a group called the Ursa Major Moving Cluster.

I'll show you that again, but leaving the current shape of the plough for comparison. So the handle becomes much more bent, but the bowl flattens out. And here's the familiar cross shape of Cygnus, the swan, as it appears today. And this is it, 100,000 years from now. What do you think that looks like?

Deneb and Alboreo don't change much, but there are big differences in the wings. Here it is again, keeping the current shape for comparison. You'll notice that the one on the left, Epsilon, really shoots off and completely disrupts the shape. And finally, here are the stars of Leo, forming the familiar shape of the crouching lion.

And these go all over the place. Even so, you might still be able to imagine something like a crouching lion out of the final result. And I'll show you that again. See, Regulus stays pretty much where it is, but look at how far Gamma Leonis travels.

It goes right across the constellation, so you'll need a pretty good imagination to make something out of that lot. And as well as those changes in shape, some stars... will actually change constellations altogether.

They'll move over the boundaries, out of their existing constellations and into their neighbours. So what's going to happen to our stellar nomenclature when that happens? Well, fortunately that's not something that we need worry about.

Those are problems. for far in the future. And just to finish off, you may know that there are companies that offer to name stars after someone you know or want to commemorate. And from time to time, organisations such as the Royal Astronomical Society get enquiries about buying star names.

Now, I'm sorry to have to tell you that such schemes have no official validity whatsoever. They're simply a novelty. So if you want something to hang on the bathroom wall, that's fine, but don't expect astronomers to take it seriously.

and you can see here what the International Astronomical Union has to say about the matter and that's the view of the Royal Astronomical Society as well well I hope I've been able to show you that the constellations aren't just about the stars they're also about poetry and art and above all human imagination And they give us a very real connection with the earliest human civilizations who looked up and imagined those first pictures in the sky. And finally, you can find the stories and histories of all the constellations, and some of the obsolete ones as well, on my website, and I've given you the address here. And I'll hand it back to you, Felicity, as my voice gives out. Thank you.

Transcript for:The History and Significance of Constellations

Transcript for:
The History and Significance of Constellations