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The nautical mile (part two)
September 4, 2023 · 5 min · 2K views
What this video covers
The nautical mile's standardized value of 1,852 meters is explained through Earth's non-spherical geometry.0:18 Earth is an oblate spheroid, with a polar radius of 6,357 km and an equatorial radius of 6,378 km — a difference of 21 km.1:39 Because Earth is not a perfect sphere, one arc-minute of latitude measures differently depending on location: 1,861 meters at the poles and 1,843 meters at the equator.2:42 The 1,852-meter value was chosen as a mean, corresponding to one arc-minute at latitude 44°20', and was formally adopted at the 1929 International Hydrographic Conference.3:48 This figure approximates a mean Earth circumference of 40,000 km.3:09 For practical navigation — maritime or aeronautical — the error introduced by treating Earth as a perfect sphere is negligible; only scientific applications requiring extreme precision are affected.4:55 The segment closes with a mention of upcoming week-long offshore navigation courses sailing the Costa Blanca and the Balearic Islands of Ibiza and Formentera.5:26
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