Eli5: What’s the difference between a mile and a nautical mile
In: 5678
A lot of units of measure are based on what was easy to measure for a person with ancient equipment.
On land, you don’t really need any equipment to measure a distance. Ancient people tended to measure things based on how many steps they took to get there. Sure, people are different sizes, but in general if 2 people walk “about 10,000 paces to the west” they’re close enough to a city or river that the differences in their strides are accounted for. So what ultimately became “a mile” on land was based on the distance a person could cover by taking a certain number of steps.
That doesn’t work so well at sea. The vast majority of humans can’t walk on water, and it’s exceptionally difficult to set up stationary landmarks to mark known distances. But people pretty quickly figured out they could use the position of the stars to get a pretty good idea of where they are, and while the equipment to do that is pretty fancy seafaring ships were also pretty expensive so it was worth installing fancy astrological equipment to help them navigate.
All of that math is based on spherical coordinates or “degrees”, so a nautical mile is based on a specific fraction of a degree. That was what was easy for sailors to measure, so it’s how they measured distance.
Latest Answers