Globes and Representations of the Cosmos

Historian and Philosopher of Science Liba Taub on a history of the globe, antique representation of the Universe, and Ptolemy’s armillary sphere

videos | July 14, 2017

The video is a part of the project British Scientists produced in collaboration between Serious Science and the British Council.

There’s a common misconception that prior to Columbus people thought the world was flat. And we have an excellent evidence that in ancient Greece and Rome many people thought that the Earth was round and, in fact, that the entire Universe, the Cosmos was spherical. We know this from reading ancient writings and we also have descriptions in writings of actual globes that were made in Antiquity. There are also some mosaics that survived, that have pictures of things that look like they might actually be globes on a stand with a person or a god, or goddess standing next to them with a pointer suggesting that these globes were being used in a teaching context.

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In terms of ancient globes, we do have some examples that survived. There’s the Farnese Atlas – that is a Roman copy of an earlier Greek globe, it survives in Naples. It doesn’t look, when you look at it, as if it is meant to be exact, but people have studied it for a long time and are continuing to study it. It’s held by a figure, Atlas, who has it on his shoulders, it’s clearly very heavy, very weighty. And there are different pictures on the globe, for instance, ships and different things being pointed out. These are meant to represent different constellations, different asterisms. There is also, for example, a fragment of a celestial globe that survives in the Neues Museum in Berlin. It’s a rather small piece of a celestial globe, but it’s also an indication that astronomical globes were actually made in Antiquity, not just written descriptions of such objects.

Globes continue to be made in later periods. We have examples from the Islamic world of astronomical globes which saw constellations, different star figures. And in the early modern period we have globes of the Earth being made as well. One of the interesting things is that when we come into the more modern period, we sometimes see pairs of globes that are made and displayed side by side, and they would be the same size. And that’s a little puzzling actually, I think when you think about it that the Earth is being represented as exactly the same size side by side with an astronomical globe of the heavens showing the constellations. And I think, that raises some interesting questions about globes and what they’re representing. I think that there’s probably an important message there -it’s that we shouldn’t take the size of the objects and even the relative size of them to one another too literally. These are representations what the accuracy is of them in modern terms is a historical question, I think, that we have to ask – what is meant to be represented here?

We also know from written accounts that there were other representations of the world and of the Universe, of the Cosmos in Antiquity. There were models of heavenly motions with the Earth in the center and planets, the Greek word refers to so-called wanderers in the sky that have different pets. Those are in contrast to the so-called fixed stars that when we look at a starry sky at night seem to all move together. And the models that are described show the Earth in the center of the Cosmos, in the center of the Universe, I think, it’s worth pointing out that a number of ancient authors, astronomers recognized that from a mathematical standpoint it doesn’t matter if the Earth is in the center of the Cosmos or the Sun, for example. That you could still account for the motions of the heavenly bodies mathematically, perfectly adequately, but as some ancient authors asked «does it feel as if the Earth is moving?» And of course, the answer for most people I think is «no».

But the sorts of astronomical models that were made in Antiquity were a sort of planetarium. Even though they don’t survive, we can look at more modern examples, for instance, from the 18th century where we see a representation of the ball representing the Earth in the center and metal arms holding planets that will show movements around that Earth. Once again here, the size of the objects isn’t accurate to represent the distance of these celestial objects from one another. What is important and shown in these objects though is the order of the celestial objects, the order of the planets in the Cosmos.

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The word «order» is very important for understanding the ancient Greek conception of the Cosmos. Because the word «cosmos» comes from a Greek word that actually refers to putting something into order,  almost tidying it up. Our modern English word «cosmetic» is related to that. So we can understand that the Greek word «cosmos» itself is referring to order and is referring in a certain way almost toward to «beauty» and to «ornament». There’s an idea that the order of the Universe, the structure of the Universe is itself beautiful.

Not many examples of ancient artifacts representing the world or the world order survive. Though we do have written accounts. For instance, in Ptolemy’s Almagest we have descriptions of different astronomical instruments and we also have a description of an instrument called an armillary sphere.
While Ptolemy’s armillary sphere does not survive, there are examples from later periods including an example in the Whipple Museum of the History of Science, the University of Cambridge, which is probably from the late medieval or early modern period. And it’s a small presumably handheld armillary sphere that might have been used for teaching rather than for observing. Not many of these survive from that period, but they continue to be made and used well into the 19th century. In fact, during the 19th century we see examples being made on printed paper, on cardboard, and wood, or we would have a so-called Ptolemaic representation of the world side by side with the Copernican representation of the world. So geocentric, Earth-centric side by side with heliocentric, Sun-centered. These would be used in a teaching environment to compare and contrast the two world systems with two actually very similar looking representations.

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While the ancient examples don’t survive themselves, they were described in writing and we have examples of later astronomers seemingly very deliberately copying or making their own versions of these earlier instruments. So we know, for instance, that Copernicus apparently made an instrument that was meant to be a Ptolemy’s model. And it’s interesting that some of the instruments that seem to have been copied were replica of what Ptolemy would have made were transmitted to other cultures. So for instance, when the Jesuit missionary astronomers went to Peking and worked in the observatory there, they brought with them the sorts of instruments that Tycho Brahe used, and some of the instruments that he built and used were based on Ptolemy’s models and instructions. If you go and visit the Beijing Observatory today you’ll see things that in some ways may actually be almost the offspring, in a certain way, of these much earlier and more ancient instruments. So while they don’t survive themselves, the ideas that were embodied in those instruments survived and later instrument makers, later astronomers sought to make a copy or a version of those instruments.

Many of us have enjoyed working with or playing with the globe when we were a child. It what may have even been a very favorite object. And I think one of the things that’s sometimes surprising is to realize that not only regular Earth globes that are geopolitical Globes were created and in different historical periods, but in Antiquity we had the first astronomical globes that showed celestial objects, that showed starry constellations. I think that that’s sometimes surprising to us that the modeling of the Universe was actually physically done in an object that’s very familiar to us in some ways and yet also rather foreign.

Professorial Fellow in History and Philosophy of Science, Director of Studies in History and Philosophy of Science, Professor of History & Philosophy of Science, Director of Whipple Museum of the History of Science, University of Cambridge
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