THE SIZE OF THE EARTH

In ancient times it was thought that the earth was flat, covered by a dome (with windows through which the rain fell) where the stars were situated and along which the sun and the moon revolved around the earth!  Then some people living near the sea, noticed that when ship sailed away the hull of the ship disappeared first while the sails were still visible and that led the to the idea that the earth was not flat!  Then they also noticed that when travelling far north or far south some stars would disappear and new ones appear!  As far as we know, the first person to state that the earth was a sphere, was a Greek named Philolaus of Tarentum who in 450 B.C. put forward this view and by 350 B.C. this was generally accepted, by learned men all over the known world and the they started speculating about the size of the earth.

Then a Greek philosopher, Eratosthenes of Cyrene (276 – 196 B.C.) was told that on summer solstice (21 June) at midday a vertical rod would cast no shadow in Syene (which was situated just about on the Tropic of Capricorn – when the sun would be directly overhead), but a rod in Alexandria, about 800 km north of Syene, would cast a short shadow, indicating that the sun was there about 7° south at the same time!  Eratosthenes then used this to calculate the circumference of the earth:  If  7° equalled 800 km, then 360° would be about 41 000 km!  Modern methods have arrived at a figure of 40 067,78 km at the equator, so hats off to mr Eratosthenes who was born 2286 years ago!

But this figure sounded too high for some people and later astronomers arrived at a figure of about 29 000 km which was accepted up to the time of Columbus who used these figures to convince his backers that he could easily reach Asia by sailing westwards over the Atlantic Ocean, but in fact it was not, because America occupied the place where they thought Asia should be!

The moral of the story:  Do not jump to conclusions!

Oupa