Spherical Earth | Wikipedia audio article
Channel: wikipedia tts
Date: 2019-05-15

This is an audio version of the Wikipedia Article:
https://en.wikipedia.org/wiki/Spherical_Earth


00:01:50 1 Cause
00:02:12 1.1 Formation
00:04:11 1.2 Later shape changes and effects
00:05:22 1.3 Shapes of other bodies
00:07:03 2 Effects and empirical evidence
00:07:40 2.1 Spacecraft
00:08:42 2.2 Aircraft
00:10:00 2.3 Visibility of distant objects
00:12:49 2.4 Lunar eclipses
00:14:00 2.5 Observation of the stars at altitude
00:15:40 2.6 Observation of the fixed stars from different locations
00:20:27 2.7 Surface circumnavigation
00:22:15 2.8 Observing the Sun
00:24:38 2.8.1 Local solar time and time zones
00:28:22 2.8.2 Length of the day
00:31:30 2.8.3 Determining the shape of the Earth
00:33:17 2.8.4 Determining the size of the Earth
00:34:08 2.8.5 Watching the Sun set twice
00:35:56 2.9 Spherical vs. flat triangles
00:37:37 2.10 Grids are distorted by spherical ground
00:39:03 2.11 Weather systems
00:39:41 2.12 Gravity
00:41:05 2.13 Technology
00:43:06 2.14 Architecture
00:43:35 3 History
00:43:44 3.1 Antiquity
00:43:53 3.1.1 Hebrew Bible
00:44:24 3.1.2 Hellenistic world
00:46:02 3.1.2.1 Pythagoras
00:46:59 3.1.2.2 Plato
00:48:21 3.1.2.3 Aristotle
00:51:23 3.1.2.4 Archimedes
00:52:02 3.1.2.5 Eratosthenes
00:53:54 3.1.2.6 Seleucus of Seleucia
00:54:20 3.1.2.7 Posidonius
00:54:53 3.1.3 Roman Empire
00:55:39 3.1.3.1 Strabo
00:56:43 3.1.3.2 Claudius Ptolemy
00:59:23 3.1.3.3 Late Antiquity
01:01:04 3.1.4 India
01:03:15 3.2 Middle Ages
01:04:25 3.2.1 Early Medieval world
01:07:14 3.2.2 Islamic astronomy
01:12:50 3.2.3 High and late medieval Europe
01:15:30 3.3 Early Modern period
01:15:40 3.3.1 Circumnavigation of the globe
01:17:31 3.3.2 Ming China
01:20:55 4 Measurement and representation
01:22:36 5 See also



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SUMMARY
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The earliest reliably documented mention of the spherical Earth concept dates from around the 6th century BC when it appeared in ancient Greek philosophy, but remained a matter of speculation until the 3rd century BC, when Hellenistic astronomy established the spherical shape of the Earth as a physical given and calculated Earth's circumference. The 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 Sebastián Elcano's expedition's circumnavigation (1519–1522).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 with a hemispherical sky-dome above, 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).
The realization that the figure of the Earth is more accurately described as an ellipsoid dates to the 17th century, as described by Isaac Newton in Principia. 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.