Who was the first man to calculate the circumference of the earth?

Answer 1

The generally accepted answer is Eratosthenes, whose reward was to have a really neat round crater on the moon named for him.

He made his calculations by recording the angles of the shadows in deep wells and thus figuring out what fraction of the earth's circumference was represented by the distance between two wells.

But the Egyptians did some things that were quite clever. They knew more than 4,000 years ago that the earth was a spherical solid suspended in open space, that the earth orbits the sun, and that there are other celestial objects that also orbit the sun.

And they did have a fairly accurate estimate of the earth's size.

Answer 2

The earliest that I know of was recorded by the Egyptians (around 2000 BCE), reported by Heraclitus. The first cleverly accurate version of course belongs to the space age, when we could measure the shape from space.

Pedantically, it will vary depending on the time of day, distance of the planets from the surface of land (or water, which reacts differently).

Answer 3

The first reasonably good measurement of the earth’s size was done by Eratosthenes, a Greek who lived in Alexandria, Egypt, in the third century B.C.

Answer 4

There were a number of folks with 'guesstimates', estimates, and calculations of varying accuracies.

Try this page for some answers:
http://en.wikipedia.org/wiki/History_of_geodesy



Best regards,
Jim