Can’t we just use the metric or imperial system? why is there a need to use this measurement that is seemingly coming from chopping the earth into half and dividing its circumference by 360 degrees, and then calculating a minute of arc of it?
Also what did I just say? The way this measurement is made makes no sense
In: 0
“Nautical” should be a hint; this kind of measurement is very useful if you are trying to navigate in the open ocean. Before GPS and other such fancy conveniences ships needed to do things like look at the relative angle of the stars at specific times in order to figure out their location on the globe.
When you are doing those kind of calculations, a unit which is defined as a meridian arc length of one minute of latitude is quite useful as opposed to some arbitrary distance.
Minutes of arc are important for measuring distance using celestial bodies. Time is necessary to calculate distance when there are no land reference
Planes track their speeds and distances in nautical miles.
Say you have two planes flying from New York to LA. One is flying at 31,000 feet and the other is at 38,000 feet. To arrive at the same time, the higher plane has to travel faster.
If both planes travel at 500 nautical miles/hr they will arrive at the same time. but if they both travel at 500 miles/hr, the lower plane will get there faster due to the fact that the higher plane is actually has a larger distance to travel in the air. Just like taking the outside corner of a turn is a longer distance.
So if air traffic control wants to know how long it will take for a plane to arrive based on speed and location, it’s much simpler to just already have everything in nautical miles instead of trying to do a bunch of math to account for altitude.
You take the circumference of the planet and divide it into 360°, which makes sense because the circumference is a circle and we usually divided circles into 360 degrees. Since the world is big a single degree is quite a lot of distance so we further subdivide a degree into 60 minutes and those minute into 60 seconds. (This is not a thing specific to geography but a general thing we do with degrees of an arc in geometry.)
A degree of longitude on the equator is more or less the same distance as a degree of latitude anywhere. (Not quite because the earth is not a perfect sphere but more of squashed potato.)
Nautical miles are easy to use with a coordinate system because 40° 43′ N, 74° 0′ W is exactly one nautical mile south of 40° 44′ N, 74° 0′ W.
The 43′ and 44′ are the minutes of an arc.
It doesn’t work as well for longitude as latitude because the earth is round by at least on the equator a minute west or east is a nautical mile.
Kilometer is sort of based on the same general idea, but instead of chopping up the distance from equator to pole into 90 degree with 60 minutes each we chop up the distance into 10,000 kilometer with 1000 meter each.
Nautical miles is an older system and has kept on because everyone was using it in boats and later planes for distance and speed (knots are nautical miles per hour).
It would make more sense to use kilometers and km/h everywhere, but people are used to nautical miles and knots and with computers it is easy to display numbers in any unit you want.
It makes much more sense if you consider the measure and the outcome of a need. All measures are arbitrary, what makes them useful is their application.
A nautical mile is a very useful measure of large distances when navigating in ships and travelling long distances and trying to locate one’s position on a map or the globe of the earth. It makes more sense than say a kilometer or mile.
Imagine a map of the world.
you’re basically trying to unwrap a globe onto a piece of paper.
So that’s going to require you distort the thing.
But if it’s distorted you will get the distances between things wrong.
So you draw lines that distort with the map to keep it right.
Now you have to draw the lines at regular intervals.
You know from school that a circle has 360 degrees.
And back then the people working with degrees didn’t do the whole decimal thing.
They were thought like time, the degrees had minutes and seconds. In fact you’re already dealing with an even division of 60, why the hell would you want to add in 10 to the equation?
There are 3600 seconds per degree like there are 360 degrees in a circle.
So now you got lines drawn at regular intervals.
And as we stated, the lines are distorted because of you unwrapping the globe, so you can’t just take a ruler and measure distances.
So now you just count the number of minute lines between two places.
That’s a nice long distance, but not too long that you miss big things.
That count of minute lines? That’s the count of nautical miles.
The whole setup is done to make it easier to navigate really far using maps.
Something that’s really important if you can’t always just look at a land mark, such as if you’re sailing or flying over an ocean.
The use of nautical miles is mostly historical. It was easier for nautical navigators to use as there was no need for converting their calculations from angles to distance as they were the same unit. And it still remain because it takes time to switch to another unit. There are still people alive today who used to navigate with sextants and slide rulers and therefore would have prefered nautical miles. It is still taught in naval achademies for use when other navigational techniques such as GPS fails. A lot of charts, laws, tools, etc. are using nautical miles still. It makes it easy to compare distances on these things to each other. If a chart uses kilometers and a tool uses nautical miles that makes it hard to use as you need to convert the values all the time. But we are seeing more and more use of both nautical miles and kilometers which allows things to work in either unit. But it takes time for everything on boats to switch to these and then we can switch units.
A nautical mile is a function of the latitude and longitude system we use for coordinates. Since the latitude and longitude system is what we use to navigate, it makes sense to use a unit natural to it. Whenever you do distance calculation, be it longitude sailing, plane sailing, or great circle sailing, if you input latitude and longitude, the arithmetic will give you an answer in nautical miles. If you look at a chart and measure off a distance on your latitude scale, you can find your distance in nautical miles.
If we used metric, we would have to convert the natural distances that we observe through navigation. Since a conversion is an extra step, we use the natural unit instead. Why convert when you don’t have to? If you truly want a metric distance for navigation, you would need to make latitude and longitude metric as well. However, since the Earth is a globe, and globes have 360°, a metric coordinate system would also oppose the basic way we calculate geometry.
it helped with navigation. If you sail 60 miles north, your latitude coordinate has changed by 60 minutes, or 1 degree.
If you use other units, you need to convert, which means doing math, on a swaying desk of a medieval ship. Paper is expensive, and so are pencils. So you will be scrawling your numbers in coal on a plank of wood, possibly in very bad light.
Can’t we just use the metric or imperial system? why is there a need to use this measurement that is seemingly coming from chopping the earth into half and dividing its circumference by 360 degrees, and then calculating a minute of arc of it?
Also what did I just say? The way this measurement is made makes no sense
In: 0
“Nautical” should be a hint; this kind of measurement is very useful if you are trying to navigate in the open ocean. Before GPS and other such fancy conveniences ships needed to do things like look at the relative angle of the stars at specific times in order to figure out their location on the globe.
When you are doing those kind of calculations, a unit which is defined as a meridian arc length of one minute of latitude is quite useful as opposed to some arbitrary distance.
Minutes of arc are important for measuring distance using celestial bodies. Time is necessary to calculate distance when there are no land reference
Planes track their speeds and distances in nautical miles.
Say you have two planes flying from New York to LA. One is flying at 31,000 feet and the other is at 38,000 feet. To arrive at the same time, the higher plane has to travel faster.
If both planes travel at 500 nautical miles/hr they will arrive at the same time. but if they both travel at 500 miles/hr, the lower plane will get there faster due to the fact that the higher plane is actually has a larger distance to travel in the air. Just like taking the outside corner of a turn is a longer distance.
So if air traffic control wants to know how long it will take for a plane to arrive based on speed and location, it’s much simpler to just already have everything in nautical miles instead of trying to do a bunch of math to account for altitude.
You take the circumference of the planet and divide it into 360°, which makes sense because the circumference is a circle and we usually divided circles into 360 degrees. Since the world is big a single degree is quite a lot of distance so we further subdivide a degree into 60 minutes and those minute into 60 seconds. (This is not a thing specific to geography but a general thing we do with degrees of an arc in geometry.)
A degree of longitude on the equator is more or less the same distance as a degree of latitude anywhere. (Not quite because the earth is not a perfect sphere but more of squashed potato.)
Nautical miles are easy to use with a coordinate system because 40° 43′ N, 74° 0′ W is exactly one nautical mile south of 40° 44′ N, 74° 0′ W.
The 43′ and 44′ are the minutes of an arc.
It doesn’t work as well for longitude as latitude because the earth is round by at least on the equator a minute west or east is a nautical mile.
Kilometer is sort of based on the same general idea, but instead of chopping up the distance from equator to pole into 90 degree with 60 minutes each we chop up the distance into 10,000 kilometer with 1000 meter each.
Nautical miles is an older system and has kept on because everyone was using it in boats and later planes for distance and speed (knots are nautical miles per hour).
It would make more sense to use kilometers and km/h everywhere, but people are used to nautical miles and knots and with computers it is easy to display numbers in any unit you want.
It makes much more sense if you consider the measure and the outcome of a need. All measures are arbitrary, what makes them useful is their application.
A nautical mile is a very useful measure of large distances when navigating in ships and travelling long distances and trying to locate one’s position on a map or the globe of the earth. It makes more sense than say a kilometer or mile.
Imagine a map of the world.
you’re basically trying to unwrap a globe onto a piece of paper.
So that’s going to require you distort the thing.
But if it’s distorted you will get the distances between things wrong.
So you draw lines that distort with the map to keep it right.
Now you have to draw the lines at regular intervals.
You know from school that a circle has 360 degrees.
And back then the people working with degrees didn’t do the whole decimal thing.
They were thought like time, the degrees had minutes and seconds. In fact you’re already dealing with an even division of 60, why the hell would you want to add in 10 to the equation?
There are 3600 seconds per degree like there are 360 degrees in a circle.
So now you got lines drawn at regular intervals.
And as we stated, the lines are distorted because of you unwrapping the globe, so you can’t just take a ruler and measure distances.
So now you just count the number of minute lines between two places.
That’s a nice long distance, but not too long that you miss big things.
That count of minute lines? That’s the count of nautical miles.
The whole setup is done to make it easier to navigate really far using maps.
Something that’s really important if you can’t always just look at a land mark, such as if you’re sailing or flying over an ocean.
The use of nautical miles is mostly historical. It was easier for nautical navigators to use as there was no need for converting their calculations from angles to distance as they were the same unit. And it still remain because it takes time to switch to another unit. There are still people alive today who used to navigate with sextants and slide rulers and therefore would have prefered nautical miles. It is still taught in naval achademies for use when other navigational techniques such as GPS fails. A lot of charts, laws, tools, etc. are using nautical miles still. It makes it easy to compare distances on these things to each other. If a chart uses kilometers and a tool uses nautical miles that makes it hard to use as you need to convert the values all the time. But we are seeing more and more use of both nautical miles and kilometers which allows things to work in either unit. But it takes time for everything on boats to switch to these and then we can switch units.
A nautical mile is a function of the latitude and longitude system we use for coordinates. Since the latitude and longitude system is what we use to navigate, it makes sense to use a unit natural to it. Whenever you do distance calculation, be it longitude sailing, plane sailing, or great circle sailing, if you input latitude and longitude, the arithmetic will give you an answer in nautical miles. If you look at a chart and measure off a distance on your latitude scale, you can find your distance in nautical miles.
If we used metric, we would have to convert the natural distances that we observe through navigation. Since a conversion is an extra step, we use the natural unit instead. Why convert when you don’t have to? If you truly want a metric distance for navigation, you would need to make latitude and longitude metric as well. However, since the Earth is a globe, and globes have 360°, a metric coordinate system would also oppose the basic way we calculate geometry.
it helped with navigation. If you sail 60 miles north, your latitude coordinate has changed by 60 minutes, or 1 degree.
If you use other units, you need to convert, which means doing math, on a swaying desk of a medieval ship. Paper is expensive, and so are pencils. So you will be scrawling your numbers in coal on a plank of wood, possibly in very bad light.
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