Why Is A Nautical Mile Longer Than A Regular Mile?


4 Answers

Cindy Thompson Profile
Cindy Thompson answered
A land mile is a set distance, whereas a nautical mile will vary slightly in length depending on how close you are to the equator. This is all to do with the way the the earth can be seperated into degrees, but because it's not perfectly round, by the time you get to the outer edge near the poles the disatnce between is greater than the distance near the equator.
it's hard to explain but if you draw an orb on the page and draw lines going from the middle out, all at the same degrees in the middle you will see that as you go further north the distance becomes larger. Each of these degrees is then divided into forty (I think, but it's been a while since I did this) and these are nautical miles, therfore at the poles a nautical mile is longer than at the eqautor. It is hard to explain without drwaing a picture but I hope you've followed my gist!
If you ever look at a sailing chart you will see this is taking into account as variability. Peace
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Anonymous commented
Not Bad!
Alexander Selkirk
A Nautical Mile was originally a minute of arc across the earth's surface. The Earth is approximately a sphere and a straight line on a sphere is a great circle. All the way around the Earth on that circle would be 360 degrees, each of which is divided into 60 minutes of arc. So then, if the Earth's radius was, say 6360 Km then the circumference would be 2*pi*6360=39961 km, divided by 360 and then by 60 would give us the length of the nautical mile as 1.85 km. But the Earth is not an exact sphere but is a spheroid. The radius at the equator is 6,378.135 km and at the poles is 6,356.750 km. Which means that the length of the nautical mile would vary between 1855 and 1849 m. For convenience, there is an international agreement that the nautical mile be defined as exactly 1852 meters.

The "regular mile", as you call it, sometimes called the "International Mile" is part of the old system of measures still used in the US for some unknown reason. The US really needs to get rid of those old measurements and start using meters and kilometers like the rest of the world.
chris monroe
chris monroe commented
the reason we still use them is because all
buildings railroads roads etc are built to these measurements so it would be impossible at this point
Henry Ben Profile
Henry Ben answered
A nautical mile (symbol nmi) is the angular distance of one minute (1/60 degree) of latitude on the earth surface. The distance varies with the difference of latitude by its original definition. Now the internation conference has fixed its defintion as exactly 1852 meters.
The statute mile (symbol mi) is an unit of distance as measured on land. One statute mile is 5280 feet or 1760 yards, which is about 1,609 metres.
Why Is A Nautical Mile Longer Than A Regular Mile? It's by their definitions.  
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David Jackson
David Jackson commented
A nautical mile is a unit of distance that is used on the water; it is equal to 1.15 miles or one minute (1/60 of a degree) of longitude. It does NOT vary according to wherever you happen to be! It is a fixed, standard measurement used both nautically and aeronautically.
Anonymous Profile
Anonymous answered
Nautical Mile stands for a unit of length used in navigation; exactly 1,852 meters; historically based on the distance spanned by one minute of arc in latitude

where as .. A regular mile is a unit of length equal to 1,760 yards or 5,280 feet; exactly 1609.344 meters
Anonymous Profile
Anonymous answered
The answers I've seen so far answer the question "What is the difference between a nautical mile and a regular mile?". Does anyone know "Why" they are different?

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