Changes

==Etymology==

==Etymology==

[https://nordan.daynal.org/wiki/index.php?title=English#ca._1100-1500_.09THE_MIDDLE_ENGLISH_PERIOD Middle English], from Medieval Latin aequator, [[literally]], equalizer, from [[Latin]] aequare

[https://nordan.daynal.org/wiki/index.php?title=English#ca._1100-1500_.09THE_MIDDLE_ENGLISH_PERIOD Middle English], from Medieval Latin aequator, [[literally]], equalizer, from [[Latin]] aequare

*Date: [http://www.wikipedia.org/wiki/14th_Century 14th century]

*Date: [https://www.wikipedia.org/wiki/14th_Century 14th century]

==Definitions==

==Definitions==

*1 : the great [[circle]] of the [[celestial]] [[sphere]] whose [[plane]] is [[perpendicular]] to the [[axis]] of the [[earth]]

*1 : the great [[circle]] of the [[celestial]] [[sphere]] whose [[plane]] is [[perpendicular]] to the [[axis]] of the [[earth]]

In simpler [[language]], the Equator is an [[imaginary]] line on the [[Earth]]'s surface [[Equal|equidistant]] from the North Pole and South Pole that divides the Earth into a Northern Hemisphere and a Southern Hemisphere. The equators of other [[planets]] and [[astronomical]] [[bodies]] are defined likewise.

In simpler [[language]], the Equator is an [[imaginary]] line on the [[Earth]]'s surface [[Equal|equidistant]] from the North Pole and South Pole that divides the Earth into a Northern Hemisphere and a Southern Hemisphere. The equators of other [[planets]] and [[astronomical]] [[bodies]] are defined likewise.

==Crossing the Equator==

==Crossing the Equator==

Certain navies, such as the [http://en.wikipedia.org/wiki/Royal_Navy Royal Navy] and the [http://en.wikipedia.org/wiki/US_Navy US Navy], have a [[tradition]] of holding [[ceremonies]] on board ship to mark sailors' first crossing of the Equator. These rites of [[initiation]] have in the past been notorious for their brutality. Milder line-crossing [[ceremonies]], typically featuring [http://en.wikipedia.org/wiki/King_Neptune King Neptune], are also held for passengers' [[entertainment]] on some civilian ocean liners and cruise ships.

Certain navies, such as the [https://en.wikipedia.org/wiki/Royal_Navy Royal Navy] and the [https://en.wikipedia.org/wiki/US_Navy US Navy], have a [[tradition]] of holding [[ceremonies]] on board ship to mark sailors' first crossing of the Equator. These rites of [[initiation]] have in the past been notorious for their brutality. Milder line-crossing [[ceremonies]], typically featuring [https://en.wikipedia.org/wiki/King_Neptune King Neptune], are also held for passengers' [[entertainment]] on some civilian ocean liners and cruise ships.

==Exact length of the Equator==

==Exact length of the Equator==

The Equator is modeled exactly in two widely used standards as a circle of radius an integer number of metres. In 1976 the [http://en.wikipedia.org/wiki/International_Astronomical_Union IAU] standardized this [[radius]] as 6,378,140 metres (20,925,656 ft), subsequently refined by the [http://en.wikipedia.org/wiki/International_Union_of_Geodesy_and_Geophysics IUGG] to 6,378,137 metres (20,925,646 ft) and adopted in [http://en.wikipedia.org/wiki/World_Geodetic_System WGS-84], though the yet more recent IAU-2000 has retained the old IAU-1976 [[value]]. In either case, the length of the Equator is by definition exactly 2π times the given [[standard]], which to the nearest millimeter is 40,075,016.686 metres (131,479,713.54 ft) in WGS-84 and 40,075,035.535 metres (131,479,775.38 ft) in IAU-1976 and IAU-2000.[1]

The Equator is modeled exactly in two widely used standards as a circle of radius an integer number of metres. In 1976 the [https://en.wikipedia.org/wiki/International_Astronomical_Union IAU] standardized this [[radius]] as 6,378,140 metres (20,925,656 ft), subsequently refined by the [https://en.wikipedia.org/wiki/International_Union_of_Geodesy_and_Geophysics IUGG] to 6,378,137 metres (20,925,646 ft) and adopted in [https://en.wikipedia.org/wiki/World_Geodetic_System WGS-84], though the yet more recent IAU-2000 has retained the old IAU-1976 [[value]]. In either case, the length of the Equator is by definition exactly 2π times the given [[standard]], which to the nearest millimeter is 40,075,016.686 metres (131,479,713.54 ft) in WGS-84 and 40,075,035.535 metres (131,479,775.38 ft) in IAU-1976 and IAU-2000.[1]

The [http://en.wikipedia.org/wiki/Geographical_mile geographical mile] is defined as one arc minute of the Equator, and therefore has [[different]] [[values]] depending on which standard equator is used, namely 1,855.3248 metres (6,087.024 ft) or 1,855.3257 metres (6,087.027 ft) for respectively WGS-84 and IAU-2000, a difference of nearly a millimeter.

The [https://en.wikipedia.org/wiki/Geographical_mile geographical mile] is defined as one arc minute of the Equator, and therefore has [[different]] [[values]] depending on which standard equator is used, namely 1,855.3248 metres (6,087.024 ft) or 1,855.3257 metres (6,087.027 ft) for respectively WGS-84 and IAU-2000, a difference of nearly a millimeter.

The [[earth]] is standardly modeled as a [[sphere]] flattened 0.336% along its axis. This results in the Equator being 0.16% longer than a [http://en.wikipedia.org/wiki/Meridian_(geography) meridian] (as a great [[circle]] passing through the two poles). The IUGG standard meridian is, to the nearest millimeter, 40,007,862.917 metres (131,259,392.77 ft), one arc minute of which is 1,852.216 metres (6,076.82 ft), explaining the SI standardization of the [http://en.wikipedia.org/wiki/Nautical_mile nautical mile] as 1,852 metres (6,076 ft), more than 3 metres (10 ft) short of the [http://en.wikipedia.org/wiki/Geographical_mile geographical mile].[http://en.wikipedia.org/wiki/Equator]

The [[earth]] is standardly modeled as a [[sphere]] flattened 0.336% along its axis. This results in the Equator being 0.16% longer than a [https://en.wikipedia.org/wiki/Meridian_(geography) meridian] (as a great [[circle]] passing through the two poles). The IUGG standard meridian is, to the nearest millimeter, 40,007,862.917 metres (131,259,392.77 ft), one arc minute of which is 1,852.216 metres (6,076.82 ft), explaining the SI standardization of the [https://en.wikipedia.org/wiki/Nautical_mile nautical mile] as 1,852 metres (6,076 ft), more than 3 metres (10 ft) short of the [https://en.wikipedia.org/wiki/Geographical_mile geographical mile].[https://en.wikipedia.org/wiki/Equator]

[[Category: Earth Science]]

[[Category: Earth Science]]