Geographical mile


The geographical mile is slightly larger than the nautical mile (which was historically linked to the circumference measured through both poles); one geographic mile is equivalent to approximately . ==Related units== It was closely related to the nautical mile, which was originally determined as 1 minute of arc along a great circle of the Earth, but is nowadays defined as exactly 1852 metres.

The value formerly used in the United States was 6 080.20 feet = 1 nautical (geographical or sea) mile." (The deprecated value, 6080.2 feet, is n) A separate reference identifies the geographic mile as being identical to the international nautical mile of 1852 metres (and slightly shorter than the British nautical mile of ).


For the international ellipsoid 1924 this equalled 1855.4 metres.

Greater precision depends more on choice of ellipsoid than on more careful measurement: the length of the equator in the World Geodetic System WGS-84 is which makes the geographical mile 1855.3248 m, while the IERS Conventions (2010) takes the equator to be making the geographical mile 1855.3250 m, 0.2 millimetres longer.


For the international ellipsoid 1924 this equalled 1855.4 metres.


The US National Institute of Standards and Technology (NIST) notes that: "The international nautical mile of 1 852 meters (6 076.115 49...feet) was adopted effective July 1, 1954, for use in the United States.


The American Practical Navigator 2017 defines the geographical mile as .

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Page generated on 2021-08-05