Who first discovered that the earth is round?

Answer 1

Aryabhatta was first discovered that the earth is round........

Answer 2

Who discovered it is more difficult to answer than who proved it. Anyone ever noticing that a ship approaching a port from the horizon appears not all at once, but the top first and then the rest, would have had to wonder why? It's almost as if the ship were cresting the top of a hill, what was it going "up" if the sea is flat? Or when travelling from one city to another over open and flat ground, why do you see the tops of the tallest structures at your destination before the rest of the buildings?
Eratosthenes noticed that on a certain day, in a certain place at noon, an obelisk [or some tall narrow structure] cast no shadow. And, that at another place a good distance away at the same time on the same day, an obelisk there did cast a shadow. If the earth was flat, then both obelisks should have no shadow. Using the length of the shadow and the distance between the two obelisks, he calculated the circumference of the round earth to within a couple thousand kilometers of what it actually is. So, I think credit for proving it should go to him. His logic was correct, as was his experimentation--so he used a guy to measure the distance who couldn't keep count or whatever, minor flaw.

Answer 3

It has actually been known that the Earth was round since the time of the ancient Greeks. I believe that it was Pythagoras who first proposed that the Earth was round sometime around 500 B.C. IIRC, he based his idea on the fact that he showed the Moon must be round by observing the shape of the terminator (the line between the part of the Moon in light and the part of the Moon in the dark) as it moved through its orbital cycle. Pythagoras reasoned that if the Moon was round, then the Earth must be round as well. After that, sometime between 500 B.C. and 430 B.C., a fellow called Anaxagoras determined the true cause of solar and lunar eclipses - and then the shape of the Earth's shadow on the Moon during a lunar eclipse was also used as evidence that the Earth was round.

Around 350 BC, the Aristotle declared that the Earth was a sphere (based on observations he made about which constellations you could see in the sky as you travelled further and further away from the equator) and during the next hundred years or so, Aristarchus and Eratosthenes actually measured the size of the Earth!

Answer 4

It is almost certain that ancient sailors and nomads must have noticed a moving horizon as they progressed. It is easy to see ships and islands half hidden by the curve of the Earth, and even on land, disatnt mountains seen across a flat plain can be half hidden over the horizon.

So, in that respect, nobody specifically discovered it. The point is that sailors and nomads would not have what they saw recorded in history.

Answer 5

There are a number of indications that the Earth's round - lunar eclipses, the way the night sky changes as you move north and south, and seeing things appear and disappear over the horizon. Who first noticed them isn't known, but Plato listed them around 400BC and Aristotle presented a reasoned argument.

Answer 6

The name is lost to time.  Some early astronomers noticed that the Earth's shadow on the Moon during lunar eclipses was always a circular arc, no matter where the Moon was relative to the Earth during the eclipse.  The only shape which always projects a circular shadow is a sphere.

Answer 7

The Earth is not round. That is the Earth is not a prefect sphere. It is an oblate spheroid, slightly flattened at the poles and slightly bulging at the Equator.


It looks like Aristotle gets most the credit.
http://en.wikipedia.org/wiki/Spherical_Earth

Answer 8

Pretty old maybe around 3100bc because around the time the surrounding circular earth bank around stone hedge is built around that time, but i think that the year may be lost to time

Answer 9

The actual name is lost in antiquity, but it was certainly well-known to the ancient Greeks. In fact one of them (Heroditus, IIRC) calculated the circumference of the planet to be about 26,000 miles. Not bad when you think about what he had to work with (the actual number is 24,900)


Doug

Answer 10

200 BC, Eratosthenes calculated, fairly accurate, the circumference of the earth.

http://en.wikipedia.org/wiki/Eratosthenes