Latest / Timbuktu: Africa's Forgotten Center of Knowledge — Fexingo History / The Timbuktu Scholar Who Measured the Stars
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- Lucas: So we've talked a lot about Timbuktu's scholars, its libraries, its legal debates. But there's one area we haven't really touched on — and it might surprise some listeners: astronomy. Not just star-gazing, but serious mathematical astronomy. Luna: Wait, in Timbuktu? In the 15th century? Lucas: Exactly. The Sankore curriculum included what they called 'ilm al-falak' — the science of the heavens. And one of the most fascinating figures was a man named Abou Bakr Ibn Ahmad al-Timbukti. He wrote a manuscript called the 'Gift of the Inquisitive for the Path of the Stars' — an Arabic title, 'Hadiyat al-Muhtadi fi Tariq al-Nujum'. Lucas: In it, he calculated the Earth's circumference. And he did it using a method that goes back to the ancient Greeks, but with his own refinements. He was working from the Ptolemaic model — the geocentric universe — but his mathematics were sophisticated. Luna: How did he calculate it without modern tools? Lucas: He used an astrolabe and a quadrant. He measured the altitude of the Sun at noon on the summer solstice, and compared it with known values from other latitudes. He also relied on the works of earlier Islamic astronomers like al-Battani and al-Zarqali, whose tables were used across the Muslim world. Lucas: His result? He gave the Earth's circumference as approximately 25,200 miles. That's remarkably close to the actual value of about 24,901 miles. For a 15th-century scholar in the Sahel, that's incredible precision. Luna: So he was using the same kind of math that Eratosthenes used? Lucas: Similar, yes. Eratosthenes used the difference in shadow angles between Alexandria and Syene. Al-Timbukti used a variant of that — but he didn't have access to multiple cities across longitudes. He had to rely on astronomical tables and clever trigonometry. Lucas: And here's the thing: his manuscript wasn't just a copy of earlier work. He added his own observations. He corrected some errors in the tables of al-Zarqali. He also discussed how to find the direction of Mecca — the qibla — using celestial calculations, which was a practical need for prayer. Luna: So astronomy and religion were tied together. Lucas: Absolutely. In Timbuktu, astronomy served both spiritual and scientific purposes. The scholars at Sankore produced almanacs for planting and harvesting, for religious festivals, for navigation across the Sahara. They built celestial globes — we have records of them in the Mamma Haidara Library. Lucas: Al-Timbukti's work is part of a broader tradition. He held a 'ijaza' — a teaching license — from Sankore. His manuscript survives in the Ahmed Baba Institute, though it's fragile. Parts of it have been digitized by the Tombouctou Manuscripts Project. Luna: I've heard some people say that African astronomy before colonialism was just folklore. This sounds like real science. Lucas: It was. And that's a prejudice we have to unlearn. The Sankore curriculum included mathematics, astronomy, law, medicine. Al-Timbukti's work was known in Cairo and Fez. Scholars corresponded across the Sahara. They were part of a global intellectual network. Lucas: There is a controversy, though. Some historians argue that his calculation of the Earth's circumference was derivative — that he simply repeated al-Battani's numbers. But the evidence in the manuscript suggests he performed his own observations. He criticizes earlier scholars for inaccuracies. Luna: So he wasn't just a copyist. He was an active researcher. Lucas: Exactly. And that's what makes Timbuktu's story so important. It wasn't just a place where books were stored. It was a place where knowledge was produced. Al-Timbukti's 'Gift of the Inquisitive' is a testament to that. Lucas: Unfortunately, after the Moroccan invasion in 1591, the intellectual life of the city declined. Many scholars were deported or killed. Manuscripts were looted. But some survived, hidden in family libraries. And today, projects are working to preserve them. Luna: It's amazing that we can still read his work, four hundred years later. Lucas: It is. And it reminds us that the history of science isn't just a European story. It's a human story. And Timbuktu was one of its brightest chapters.