Determining the earth's shape
Today, when
you ask anyone to describe the shape of the earth, they immediately tell you it
is round. Of course, they mean that it's round like a ball, not round like a
circle or a disk. To be more precise, we would say its shape is spherical.
While today a discussion about the earth's shape may be a matter of semantics,
historically, the shape of the earth has not enjoyed such a wide consensus.
In 3000
By 500
The ancient Greeks liked geometric shapes and the mathematical harmony of nature. This preference probably influenced their speculations about the shape of the earth.
Supported
by scientific observations, such as that of the silhouette of the earth on the
moon during a lunar eclipse, Pythagoras' assumption eventually proved correct.
By the European Middle Ages, most scholars accepted the sphere as the earth's true shape, but many non-scientists still believed the earth was flat. With the coming of the Renaissance and the rediscovery of ancient Greek texts, the flat earth theory reluctantly gave way to that of the sphere
Using a circle's diameter as an axis and rotating the circle 360 degrees creates a perfect sphere.