Spherical Earth

The concept of a spherical Earth dates back to ancient Greek philosophy from around the 6th century BC, but remained a matter of philosophical speculation until the 3rd century BC when Hellenistic astronomy established the spherical shape of the earth as a physical given. The Hellenistic paradigm was gradually adopted throughout the Old World during Late Antiquity and the Middle Ages. A practical demonstration of Earth's sphericity was achieved by Ferdinand Magellan and Juan Sebastian Elcano's expedition's circumnavigation (1519−1521).

The concept of a spherical Earth displaced earlier beliefs in a flat Earth: In early Mesopotamian mythology, the world was portrayed as a flat disk floating in the ocean and surrounded by a spherical sky, and this forms the premise for early world maps like those of Anaximander and Hecataeus of Miletus. Other speculations on the shape of Earth include a seven-layered ziggurat or cosmic mountain, alluded to in the Avesta and ancient Persian writings (see seven climes), or a wheel, bowl, or four-cornered plane alluded to in the Rigveda.

The realization that the figure of the Earth is more accurately described as an ellipsoid dates to the 18th century (Maupertuis). In the early 19th century, the flattening of the earth ellipsoid was determined to be of the order of 1/300 (Delambre, Everest). The modern value as determined by the US DoD World Geodetic System since the 1960s is close to 1/298.25.

Read more about Spherical EarthSummary of Evidence For A Spherical Earth, Geodesy

Other articles related to "spherical earth, earth, spherical":

Meteorology (Aristotle) - Spherical Earth
... The earth is surrounded by water, just as that is by the sphere of air, and that again by the sphere called that of fire." (354b23-25) Aristotle is ...
Greek Philosophy - Necessity of A Counter-Earth
... By 500 BC most contemporary Greek philosophers considered the Earth to be spherical — there was obvious evidence for this from the behavior of objects near the ... This meant that all objects on the surface of the Earth had to be attracted to its center in some way otherwise, they would fall off ... stars and planets, to float above the Earth in relation to its center, because otherwise they would presumably move rapidly away ...
Spherical Earth - Geodesy
... is the scientific discipline that deals with the measurement and representation of the Earth, its gravitational field and geodynamic phenomena (polar motion, Earth tides, and crustal motion ... aspects of their temporal variations, although it can also include the study of Earth's magnetic field ... which is concerned with measuring the Earth on a global scale, and surveying ("Ingenieurgeodäsie"), which is concerned with measuring parts of the surface ...
Sphaera Mundi - Content - Spherical Earth
... Though principally about the universe, De sphaera contains a clear description of the Earth as a sphere which agrees with widespread opinion in Europe during the higher Middle Ages, in contrast to statements of some 19th- and 20th-century historians that medieval scholars thought the Earth was flat. ...

Famous quotes containing the word earth:

    I am sure my bones would not rest in an English grave, or my clay mix with the earth of that country. I believe the thought would drive me mad on my death-bed could I suppose that any of my friends would be base enough to convey my carcass back to her soil. I would not even feed her worms if I could help it.
    George Gordon Noel Byron (1788–1824)