**What is a nautical mile, and how does it differ from a normal mile and a kilometer?**

A **nautical mile** is based on the circumference of the planet Earth. If you
were to cut the Earth in half at the equator, you could pick up one of the halves and look at the equator as a circle. You
could divide that circle into 360 degrees. You could then divide a degree into 60 minutes. A minute of arc on the planet Earth
is 1 nautical mile. This unit of measurement is used by all nations for air and sea travel.

A **knot** is a unit of measure for speed. If you are traveling at a speed of
1 nautical mile per hour, you are said to be traveling at a speed of 1 knot.

A kilometer is also defined using the planet Earth as a standard of distance. If
you were to take the Earth and cut it in half along a line passing from the North Pole through Paris, and then measure the
distance of the curve running from the North Pole to the equator on that circle, and then divide that distance by 10,000,
you would have the traditional unit for the kilometer as defined in 1791 by the French Academy of Sciences.

A nautical mile is 1,852 meters, or **1.852 kilometers**. In the English measurement
system, a nautical mile is **1.1508 miles**, or 6,076 feet.

To travel around the Earth at the equator, you would have to travel (360 * 60) 21,600
nautical miles, 24,857 miles or 40,003 kilometers