Nautical mile ) is known as the geographical mile. Nautical mile A nautical mile (also known as an air mile) is a unit of measurement defined as exactly . Historically, it was defined as one minute of latitude, which is one sixtieth of a degree of latitude – i.e. since a minute of a degree is x = , the Earth's polar circumference is approximately 21,600 nautical miles. It is a non-SI unit which today has a continued use in both air and marine navigation, and for the definition of territorial waters. There is no single internationally agreed symbol. While using M
The Nautical Almanac The Nautical Almanac The Nautical Almanac has been the familiar name for a series of official British almanacs published under various titles since the first issue of "The Nautical Almanac and Astronomical Ephemeris", for 1767: this was the first nautical almanac to contain data dedicated to the convenient determination of longitude at sea. It was originally published from the Royal Greenwich Observatory in England. A detailed account of how the publication was produced in its earliest years has been published by the National Maritime Museum. Since 1958 (with the issue for the year 1960), [[Her Majesty's Nautical Almanac Office]] and