The shape of Planet Earth

Planet Earth is not exactly a sphere. It is rounded but it has a bulge around the equator and is flattened in the poles. Pole to pole diameter is about 27 miles (43 km) shorter than equatorial diameter. The rotation of the Earth is what causes the equatorial bulge.

Pythagoras, an early Greek philosopher (c. 570-500 b.C.), was one of the first to think that Earth shape could be spherical. This idea was suggested when he saw ships approaching from the horizon: at first he could see the masts, only when they approached he could start to see the rest of the ships.

Interested? Want to read more? You can find more about this subject here:

http://en.wikipedia.org/wiki/Earth
http://en.wikipedia.org/wiki/Figure_of_the_Earth