If you have ever taken a trip by boat or plane, you will surely have heard of nautical miles And knots instead of kilometers and kilometers per hour. But have you ever wondered why those who sail or fly don’t use the same units of measurement as us? And, above all, why are there two different types of “mile”? The answer is not a simple historical whim, but has to do with the very shape of our planet. But to understand the whole story and why one nautical mile equals 1,852 meters we must start by understanding what the terrestrial mile is.
What is the terrestrial mile and where does it come from
The concept of “mile” has a very ancient origin that dates back toAncient Rome. The word itself comes from Latin thousand passeswhich literally means “a thousand steps”. But be careful: for the Romans, a “step” was not the single one we take today, but rather a double step. This meant that one Roman mile corresponded to approx 1,482 meters. With the fall of the Roman Empire, things became quite complicated: each country, region or historical era began to define its “mile” differently. They ranged from the very small Egyptian mile of just 0.58 km up to the mammoth Norwegian mile from ben 11.3 km! Just think that between the 15th and 18th centuries in Europe there were approximately 46 different units of measurement all called “mile”. Today, when we talk about terrestrial millet (also called statute mile in Anglo-Saxon countries), we refer to the measurement standardized mainly in the United States and the United Kingdom, which is exactly equivalent to 5,280 feetthat is, approximately 1,609 meters.
One nautical mile is equal to 1,852 meters
If the land mile is a “linear” measurement suitable for flat roads, at sea (and in the sky) things change due to the earth curvature. And this is where the international nautical milestandardized in 1929 during the International Hydrographic Conference in Munich at exactly 1,852 meters. But why exactly this figure? The nautical mile is not a measure invented on the table, but is closely linked to the geographical coordinates of latitude and longitude. Imagine cutting the Earth in half along a meridian, resulting in an average circumference of about 40,000 kilometers. If we divide this perfect circle into 360 degrees and then we divide each individual degree into 60 arc minuteswe get that 1 minute latitude it matches exactly 1 nautical mile.
So what changes in practice compared to the land mile? First of all, lin length: The nautical mile is longer than the land mile. To be precise, 1 nautical mile is equivalent to approximately 1.15 statute miles. Secondly the comfort Of navigation: Nautical charts use the latitude and longitude grid. If a navigator or pilot needs to plot a route, he does not need to do complex mathematical calculations: he just needs to measure the distance on the map using the latitude minute scale printed on the side of the map. One minute of arc is always equal to one nautical mile. And finally knots also come into play, i.e. the value used to express the speed at sea and in the air. Navigate at the speed of 1 knot means to travel exactly 1 nautical mile per hour. This allows for immediate calculations: if you sail at 10 knots along a meridian for an hour, you instantly know you’ve covered 10 minutes of latitude on the map!
In summary, while the land mile is the result of history and the steps of the Roman army, the nautical mile is the result of geometry of our planetmaking it still today an irreplaceable tool for orienting yourself across the oceans and skies around the world.
