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by dwighttk 2560 days ago
>Only if that minute of arc lies on a great circle route.

I'm pretty sure to derive a nautical mile you have to use the equator, not just any great circle, because the earth isn't a sphere.

1 comments

Nope. It's is derived from latitude, which is an angle measured at the centre of the Earth, and not the surface.

So you have the equator, and then 90 degrees north and south. Take one of those degrees, divide it by sixty (arc-minute), project it on the surface, and you have a nautical mile. That's regardless of where you are on the surface.

That's the original/historical definition; now it's 1852m.

ah