Flat Earth: Encyclopedia II - Flat Earth - Antiquity

Flat Earth - Antiquity

Belief in a flat Earth is found in humankind's oldest writings. In early Mesopotamian thought the world was portrayed as a flat disk floating in the ocean, and this forms the premise for early Greek maps like those of Anaximander and Hecataeus.

By classical times an alternative idea, that Earth was spherical, had appeared. This was espoused by Pythagoras apparently on aesthetic grounds, as he also held all other celestial bodies to be spherical. Aristotle provided physical evidence for the spherical Earth:

• Ships actually recede over the horizon, disappearing hull-first. In a flat-earth model, they should simply get smaller and smaller until no longer visible, assuming that light travels in a straight line.
• Travelers going south see southern constellations rise higher above the horizon. This is only possible if their "straight up" direction is at an angle to northerners' "straight up". Thus the Earth's surface cannot be flat.
• The border of the shadow of Earth on the Moon during the partial phase of a lunar eclipse is always circular, no matter how high the Moon is over the horizon. Only a sphere casts a circular shadow in every direction, a circular disk casts an elliptical shadow in most directions.

The Earth's circumference was estimated around 240 BC by Eratosthenes. Eratosthenes knew that in Syrene (now Aswan), in Egypt, the sun was directly overhead at the summer solstice. He used geometry to come up with a circumference of 252,000 stades, which, depending on the length of the stadion unit, is within 2% and 20% of the actual circumference, 40,008 kilometres.

During this period the Earth was generally thought of as divided into climes, with frigid climes at the poles and a deadly torrid clime at the equator. Beyond the torrid clime were the antipodes (people living on the opposite side of a spherical Earth, so called because their feet would be turned towards the opposite direction).

Lucretius was opposed to the concept of a spherical Earth, because he considered the idea of antipodes absurd. But by the 1st century, Pliny the Elder was in a position to claim that everyone agrees on the spherical shape of the Earth (Natural History, 2.64), although there continued to be disputes regarding the nature of the antipodes, and how it is possible to keep the ocean in a curved shape. Interestingly, Pliny as an "intermediate" theory considers also the possibility of an imperfect sphere, "shaped like a pinecone" (Natural History, 2.65)

Adapted from the Wikipedia article "Antiquity", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki