# QuickCheck: Did Christopher Columbus prove the Earth is round?

IN 1492, Christopher Columbus sailed from Spain to the New World not only to find an alternative passage to India, but to prove that the world was round.

Is it true?

Verdict:

FALSE

When Christopher Columbus was at the court of Ferdinand II of Aragon and Isabella I of Castile (collectively the King and Queen of Spain), Columbus’s argument with court advisers was not about the issue whether the world was flat or round, but about the size of the Earth’s circumference.

In the 1400s, it was common knowledge that the world was a globe.

From the sixth century BC. J.-C., Pythagoras had described the Earth as a sphere. He was later supported by Aristotle and Euclid in their works.

The philosopher Plato (400 BCE) said the earth’s circumference was 64,412 km.

Some 150 years later, the mathematician Archimedes estimated it at 48,309 km.

It is unclear exactly how Plato or Archimedes arrived at their calculations, but Plato’s measurement was 60% off and Archimedes’s 20%. At least they were progressing.

Eratosthenes’ observations and calculations eventually resulted in accurate estimates of the Earth’s size.

In the third century BC. AD, Eratosthenes, a Greek librarian from Alexandria, Egypt, determined the Earth’s circumference to be 40,250 to 45,900 km by comparing the relative position of the Sun at two different locations on the Earth’s surface. Earth.

Today, the circumference of the earth is generally accepted at 40,096 km. If you take the lowest estimate attributed to Eratosthenes, his error was less than 1% – a phenomenal calculation.

What this shows is that the true circumference of the Earth had been accurately calculated nearly 2,000 years before Christopher Columbus made his voyage to the Americas.

Christopher Columbus, however, relied on calculations from Ptolemy’s book, “Geography”, which calculated the circumference of the Earth at 28,985 km, an error of 28%.

It then fell on a continent that was hiding within that 28% margin of error.

While it is true that after the fall of the Roman Empire many Europeans had succumbed to the idea that the Earth was flat, the idea has been kept alive and well in the Islamic world.

By the time of Columbus, Europe had caught up with and in some ways surpassed the knowledge of ancient Greece.

Several books published between 1200 and 1500 discussed the spherical shape of the Earth, including “The Sphere” which was written in the early 1200s, almost 300 years before Christopher Columbus.

The references:

1. https://archive.org/details/columbusforgoldg00dyso_0/