Great-circle navigation is the practice of navigating a vessel (such as a ship or aircraft) along a track that follows a great circle. A great circle track is the shortest distance between two points on the surface of the earth.

Methods

In order to construct a great circle track, the navigator of a ship may employ several methods.

Gnomonic chart

A straight line drawn on this chart would represent a great circle track. When this is transferred to a Mercator chart, it becomes a curve. The positions are transferred at a convenient interval of longitude and this is plotted on the Mercator chart with the appropriate latitude.

Spherical trigonometry

Mathematically, it is possible to determine the distance of a great circle track between two known positions. Other features of the great circle track may also be calculated.

Computer software

Software is available that allows a navigator to input a departure and arrival position to create a list of waypoints which follow a great circle track. Normally, such programs will also calculate the total distance, the distance between successive waypoints, and the courses to be followed between successive waypoints.

* Great circle
* Great circle distance
* Rhumb line

Resources

* [http://mathworld.wolfram.com/GreatCircle.html Great Circle &ndash; from MathWorld] Great Circle description, figures, and equations. Mathworld, Wolfram Research, Inc. c1999
* [http://gc.kls2.com/ Great Circle Mapper] Interactive tool for plotting great circle routes.
* [http://williams.best.vwh.net/gccalc.htm Great Circle Calculator] deriving (initial) course and distance between two points.
* [http://www.acscdg.com/ Great Circle Distance] Graphical tool for drawing great circles over maps. Also shows distance and azimuth in a table.

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Great-circle distance — The great circle distance is the shortest distance between any two points on the surface of a sphere measured along a path on the surface of the sphere (as opposed to going through the sphere s interior). Because spherical geometry is rather… …   Wikipedia

• great circle route — ▪ navigation       the shortest course between two points on the surface of a sphere. It lies in a plane that intersects the sphere s centre and was known by mathematicians before the time of Columbus. Until the 19th century ships generally… …   Universalium

• great-circle sailing — noun : the navigation or conducting of a ship on a great circle track or on a course determined in relation to a great circle track compare sailing * * * /grayt serr keuhl/, Navig. sailing between two points more or less according to an arc of a… …   Useful english dictionary

• navigation — I (New American Roget s College Thesaurus) Travel on water Nouns 1. navigation; celestial navigation, dead reckoning; circumnavigation; pilotage, steerage; seamanship; navigability. 2. (active boating) boating, yachting, yacht racing, sailing,… …   English dictionary for students

• navigation — navigational, adj. /nav i gay sheuhn/, n. 1. the act or process of navigating. 2. the art or science of plotting, ascertaining, or directing the course of a ship, aircraft, or guided missile. [1520 30; < L navigation (s. of navigatio) a voyage.… …   Universalium

• Great Lakes — This article is about the Great Lakes of North America. For the region, see Great Lakes region (North America). For other uses of this term, see Great Lakes (disambiguation). A rare cloudless satellite view of the entire Great Lakes region, April …   Wikipedia

• History of navigation — In the pre modern history of human migration and discovery of new lands by navigating the oceans, a few peoples have excelled as sea faring explorers. Prominent examples are the Phoenicians, the ancient Greeks, the Persians, the Arabians, the… …   Wikipedia