Never Mind the Bullocks, Here's the Science by Karl Kruszelnicki

was flat and that Columbus would simply sail off its edge.
    In fact, people have known the Earth to be a ball (or a sphere) for a long time.
    The biographer Samuel Eliot Morison wrote in his Pulitzer Prize-winning biography of Christopher Columbus: ‘…for of all the vulgar errors associated with Columbus, the most persistent and the most absurd is that he had to convince people “the world was round”. Every educated man in his day believed the world to be a sphere, every European university so taught geography, and seamen…knew perfectly well that the surface of the globe was curved.’
‘The Last Iconoclast Dies’
This was the headline in The Fortean Times when Charles Kenneth Johnson, President of the International Flat Earth Society, died in Lancaster, California, on 19 March 2001.
Samuel Shenton and his wife, Lillian, from Dover in the UK, had founded the International Flat Earth Society in 1956. Charles Johnson became the leader of the society when Shenton died in 1971.
Johnson had embraced the Flat Earth belief when he was just eight years old. ‘When I was at school, the first maps I saw were flat. Then Roosevelt flooded all the classrooms with globes. Well, I didn’t believe it.’
He maintained that our world was a circle of unknown size, with the North Pole in the middle, the South Pole on the circumference, and the whole thing surrounded by a wall of ice approximately 50 m high (the Antarctic ice). The Moon and the Sun, he claimed, were the same size – about 50 km across – and they circled above the disc of the Earth at a height of about 4,800 km. They didn’t touch the sky, which itself was a dome reaching to a height of about 6,400 km. And sunrise and sunset – easy, just optical illusions.
    History of Round Earth
    About 2,500 years ago, Pythagoras (c. 582-c. 507 BC) postulated that the Earth was spherical, not just a flat circular disc. He did this for aesthetic reasons, because a sphere was supposedly perfect.
    Aristotle (384-322 BC) agreed. But he had some experimental evidence.
    First, there are the lunar eclipses, where the shadow of the Earth falls on the Moon. These happen at many different times—when the Moon is close to the horizon, or when it is high in thesky. So, if the Earth were a flat disc, every now and then there would be a lunar eclipse in which the light of the Sun would hit the supposed disc of the Earth at an angle, not square on. This would produce an ellipse on the surface of the Moon. But, instead, every lunar eclipse has the Earth throwing a circular shadow onto the Moon. Aristotle wrote: ‘The sphericity of the earth is proved by the evidence of…lunar eclipses. For whereas in the monthly phases of the moon, the segments are of all sorts—straight, gibbous (convex), crescent—in eclipses, the dividing line is always rounded. Consequently, if the eclipse is due to the interposition of the Earth, the rounded lines result from its spherical shape.’ The conclusion is obvious—the Earth has to be spherical.
    Second, said Aristotle, sailors knew that when seeing a distant ship, they would first glimpse the top of the mast before sighting the rest of the ship. Once again, this shows that the Earth has to be round.
    And, third, some southern constellations rise only a little above the horizon in the Northern Hemisphere. But, said Aristotle, when travellers went further south, they saw these constellations rise higher in the sky. This could not happen with a flat Earth—but could with a spherical Earth.
    About a century later, Eratosthenes of Cyrene (c. 276-c. 194 BC), the Third Librarian of Alexandria, did some very simple geometry based on the length of shadows. He estimated the circumference of the spherical Earth—and got very close to the correct figure!
    And well into the next millennium, around 830 AD, the Muslim astronomer al-Farghani, working with other astronomers of Calif al-Ma’mun, undertook a series of measurements. They measured the Earth’s