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by jan_g 263 days ago 

    A nautical mile is ~6,076 feet or exactly 1,852 meters (???).
That is actually defined by distances on Earth (which is of course an approximation, but still ...). So, 1 nautical mile equals to one minute in the 90 degrees hemisphere arc. It's approximately 10k km from equator to the pole, so 10,000km/90/60 equals 1.852km.
1 comments
alephnil 263 days ago
> 1 nautical mile equals to one minute in the 90 degrees hemisphere arc

The nautical mile is not an SI unit, so it is not defined by a single organization, Your definition used to be the common definition, but it seems like the relevant organizations has updated the definition to be exactly 1852 m. If the original definition of the meter applies, then it would have been 1851.85 or 15 cm shorter, but with newer measurement of the earth, it would have been more like 1855 m.

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throw0101c 263 days ago
> The nautical mile is not an SI unit, so it is not defined by a single organization

"In 1929 the International Hydrographic Bureau obtained an agreement from a large number of countries to adopt a value of 1852 metres for the nautical mile, the unit thus defined to be called the International Nautical Mile."

* https://usma.org/laws-and-bills/adoption-of-international-na...

* https://en.wikipedia.org/wiki/International_Hydrographic_Org...

But there was no treaty or anything with a fancy ceremony, just a 'handshake', and so it was up to each country to adopt it with a domestic law or regulation, which (e.g.) the US did in 1954:

* https://usma.org/wp-content/uploads/2015/06/Nautical-Mile.pd...

Previously in the US it was 1853.25 m (because the US is actually metric "officially": all of its customary units (ft, oz) are defined in terms of metric equivalents):

* https://usma.org/laws-and-bills/mendenhall-order

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