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With a spherical Earth, half the planet is in daylight at any given time and the other half experiences nighttime. When a given location on the spherical Earth is in sunlight, its antipode – the location exactly on the opposite side of Earth – is in darkness. The spherical shape of Earth causes the Sun to rise and set at different times in ...
Medieval artistic representation of a spherical Earth – with compartments representing earth, air, and water (c. 1400) The Erdapfel, the oldest surviving terrestrial globe (1492/1493) The spherical shape of the Earth was known and measured by astronomers, mathematicians, and navigators from a variety of literate ancient cultures, including ...
The concept of a spherical Earth dates back to around the 6th century BC, [2] but remained a matter of philosophical speculation until the 3rd century BC. The first scientific estimation of the radius of the Earth was given by Eratosthenes about 240 BC, with estimates of the accuracy of Eratosthenes's measurement ranging from −1% to 15%.
The Old Bedford River, photographed from the bridge at Welney, Norfolk (2008); the camera is looking downstream, south-west of the bridge. The Bedford Level experiment was a series of observations carried out along a 6-mile (10 km) length of the Old Bedford River on the Bedford Level of the Cambridgeshire Fens in the United Kingdom during the 19th and early 20th centuries to deny the curvature ...
Between 640 and 720 million years ago, the Earth was covered in ice, snagging it the modern nickname “Snowball Earth.” Recently, researchers found a rock formation that shows the transition ...
However, it contains clear proofs of Earth's sphericity in the first chapter. [89] [90] Many scholastic commentators on Aristotle's On the Heavens and Sacrobosco's Treatise on the Sphere unanimously agreed that Earth is spherical or round. [91] Grant observes that no author who had studied at a medieval university thought that Earth was flat. [92]
THAAD is designed to stop incoming missiles in their terminal, or descent, phase of flight, while Aegis makes its intercept in the mid-course phase, outside Earth’s atmosphere, before the ...
However, a spherical harmonics series expansion captures the actual field with increasing fidelity. If Earth's shape were perfectly known together with the exact mass density ρ = ρ(x, y, z), it could be integrated numerically (when combined with a reciprocal distance kernel) to find an accurate model for Earth's gravitational field. However ...