Finding the earth's circumference?

Question

How can you find the earth circumferenc with a tall pole?

I heard about it before but I can't seem to find it

Answer 1

You couldn't find out with a tall pole, but you could using the Pharos (Lighthouse) of Alexandria, which is precisely what Eratosthenes of Cyrene did 2200 years ago.

I'm not going to repeat what this link says, because it sums it up quite well.

http://en.wikipedia.org/wiki/Eratosthene... (under Eratosthenes' measurement of the Earth's circumference)

or

http://www.mlahanas.de/Greeks/Eratosthen...

On a side note, I have no idea what the above answerer is babbling about. We know what the diameter of the Earth is by several mechanisms, (it's roughtly 12.5 thousand km) and using that we can calculate the circumeference (C = pi x diameter) to be around 40,000km at the equator.

I would disregard what she says - "We don't know the diameter of the Earth." Erm yes we do. And "We can work out the Earth's surface." Surface? As in the surface area of the Earth? Or the curvature? Either one can let us calculate the diameter.

Answer 2

No one can really find the circumference of the world the diameter is so big it has no number. You need the formula witch is C=pi x D or circumference equals 3.14 multiplied by the diameter, but since we don't know the diameter we can calculate the earths surface. Pressing the pi button on a calculator will show you an example of the earths surface but it just keeps going on and on forever.