Photo: John Loo (Flickr)
Love songs tell us that a real lover would walk five hundred miles and go someplace across the sea to find true love. For those charting a sentimental journey over land and sea, A Moment of Science would like to clarify a small point of navigation: the difference between a mile on land and a nautical mile.
Miles And Miles
The familiar land mile is 5,280 feet, is called a statute mile, and it’s based on paces.
On the other hand, the nautical mile is used for distances on the ocean and doesn’t have a tangible equivalent like paces. It’s a mathematical calculation based on degrees of latitude around the equator.
The equator is a circle, which we know has 360 degrees. Each degree is divided into sixty minutes, which are not the same as the minutes on your watch. In navigation, one minute is called a nautical mile. So each degree of latitude is sixty minutes or sixty nautical miles.
To put it another way, at 6,076 feet a nautical mile is longer than a statute mile, which has only 5,280 feet.
So, if our poor loverboy has to travel five hundred miles to find his sweetheart, he might have to walk five hundred statute miles which is over two million feet, or he might have to sail — or swim — five hundred nautical miles, which is over three million feet. On the other hand, he could just ignore love songs altogether, and stick with the girl next door.