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Islamic Views on the Shape of the Earth: Difference between revisions
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Islamic Views on the Shape of the Earth (view source)
Revision as of 00:06, 2 October 2016
, 2 October 2016→Oblate and prolate spheroids
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[[File:Oblate-Prolate-egg.jpg|left|465|An oblate spheroid (top left), a prolate spheroid (bottom left), and an ostrich egg, which is a prolate spheroid however you hold it]] | [[File:Oblate-Prolate-egg.jpg|left|465|An oblate spheroid (top left), a prolate spheroid (bottom left), and an ostrich egg, which is a prolate spheroid however you hold it]] | ||
The Earth is very nearly, but not absolutely a perfect sphere. It is in fact an oblate spheroid, which means that the radius from its centre to either of its two poles is shorter than the radius to the equator. In other words, there is a very slight bulge around the equator. The radius from the centre of the Earth to the north or south poles is 6,357km, and the radius from the centre to the equator is 6,378km, a difference of less than 1 percent. This is caused by the rotation of the Earth around its polar axis, which produces a centripetal force that is greatest at the equator. | The Earth is very nearly, but not absolutely a perfect sphere. It is in fact an oblate spheroid, which means that the radius from its centre to either of its two poles is shorter than the radius to the equator. In other words, there is a [[w:equatorial bulge|very slight bulge]] around the equator. The radius from the centre of the Earth to the north or south poles is 6,357km, and the radius from the centre to the equator is 6,378km, a difference of less than 1 percent. This is caused by the rotation of the Earth around its polar axis, which produces a centripetal force that is greatest at the equator. | ||
An ostrich egg, much like all eggs, can be described as a prolate spheroid. This is because the radius from its centre to either of its two poles is longer than the radius to the equator, as though it were a sphere that had been pulled from two ends. It certainly is not an oblate spheroid. You can see in the image an oblate spheroid (top left), and a prolate spheroid (bottom left). Even holding an egg on its side (top), you cannot make it look like an oblate spheroid in 3D. They are fundamentally different shapes. The shape of the ostrich egg is in fact like a prolate spheroid (bottom). No matter how you hold the egg, it is a prolate spheroid and not an oblate spheroid. | An ostrich egg, much like all eggs, can be described as a prolate spheroid. This is because the radius from its centre to either of its two poles is longer than the radius to the equator, as though it were a sphere that had been pulled from two ends. It certainly is not an oblate spheroid. You can see in the image an oblate spheroid (top left), and a prolate spheroid (bottom left). Even holding an egg on its side (top), you cannot make it look like an oblate spheroid in 3D. They are fundamentally different shapes. The shape of the ostrich egg is in fact like a prolate spheroid (bottom). No matter how you hold the egg, it is a prolate spheroid and not an oblate spheroid. | ||