A Short History of Geocentrism
The stars are like letters that inscribe themselves at every moment in the sky… Everything in the world is full of signs… All events are coordinated.
— Plotinus, from Enneads (c. 268 AD)
In astronomy, geocentrism refers to models and cosmologies that place the Earth at the centre of the universe. Geocentric models varied in their precise formulation, but they tended to assume that celestial objects — the Sun, Moon, planets, and stars — orbited around the Earth, which remained in a fixed position.
These systems, which predominated Western, Islamic, and Far Eastern cosmogonies for centuries, can seem primitive to us now that we know the truth. But we should not be so quick to pass judgement on our predecessors — not least because there’s an excellent chance that something we take for granted in our current understanding of the cosmos will end up being just as wrong. Instead, we should recognise that these early models of the universe represent that very human desire to understand the universe and our place in it.
Writing in the 13th century, William of Occam hit upon a profound wisdom when he formulated his philosophical razor — that the simplest explanation is often the best one. To the greatest minds of his time, a geocentric model remained the most simple explanation. After all, from our earthbound perspective the Earth feels entirely stationary, while the Sun and stars move across the sky as if they’re rotating around us. Similarly, the stars are so much further away from us than they could have ever imagined, so their reasoning that if the Earth did move they’d be able to see evidence of a change in star positions, was not so wrongheaded.1
The ancients believed the movements of celestial objects profoundly influenced events here on Earth. Thus, it was vital that they map the cosmos, tracking the Moon, planets, and star constellations as they arced across the heavens. In doing so, they developed complex mathematics, philosophies, and birthed the science of astronomy.
What follows is a short history of geocentrism, and how ancient astronomers in Babylon, Greece, and the Roman Empire made sense of their place in the cosmos, and how European Christendom adapted these ideas into its theology.2
Though references to celestial omens, star lists, and schemes of daylight length begin to appear in the archaeological record as far back as the 16th century BC, it was during the 8th and 7th centuries that Babylonians first developed an empirical approach to the study of the heavens. Their detailed reports on the movements of stars, the phases of the Moon, and eclipses of the Sun herald the beginnings of human science. In the words of Asger Aaboe, “we claim Babylonian mathematical astronomy as the common ancestor of modern efforts in the exact sciences.”
Unfortunately, the ancient Babylonians’ work comes down to us in fragments, scattered and piecemeal, so we’re not able to fully reconstruct their cosmology. However, the c. 7-8th century BC Imago Mundi, the first ever map of the world, suggest the Babylonians viewed the Earth as a flat disc surrounded by water.