The Shape of the Earth
The shape of planet Earth has fascinated scientists, philosophers and cultures throughout history. For thousands of years man has observed and studied the Earth. Through observations, spiritual beliefs and empirical findings, many theories developed regarding the shape of the Earth. How has our understanding of the shape of the Earth changed over time?
• Most ancient cultures, such as the Sumerians, Babylonians, even Greece , until the 5th or 6th century B.C., believed that the Earth was flat. (Garwood, 2007, p. 16)
• The Egyptians believed the universe was rectangular-shaped with four pillars that supported a flat ceiling. Egypt was in the center of a ...view middle of the document...
The town of Alexandria is directly north of Syene (on the same meridian), and on that same day vertical poles do cast shadows, because the sun is then 7.2° from the zenith. Eratosthenes assumed this to be due to the earth's curvature.” (According to Simanek, 2006) Eratosthenes reasoned that the Sun’s rays are parallel, at the two points he ways examining, because the Sun is very far away. If the Earth was flat, the Sun’s rays would be in the same spot at both locations. Eratosthenes calculated the circumference of the Earth to be a little over 24,662 miles. This is remarkably close to our current value of 24,900 miles.
• Ferdinand Magellan was the first noted person to circumnavigate and demonstrate the spheroidal shape of the Earth. The voyage lasted from August 10, 1519-September 6, 1522. “A circumnavigation alone does not prove that the earth is spherical. It could be cylindric or irregularly globular or one of many other shapes. Still, combined with trigonometric evidence of the form used by Eratosthenes 1,700 years prior, the Magellan expedition removed any reasonable doubt in educated circles in Europe.” (“Spherical Earth,” n.d.)
• We can observe ships as they go out to sea. As they approach the horizon, the ships gradually go down, first the hull, then the masts and so on. As they arrive just the opposite occurs. This suggests that the Earth’s surface curves downward.