NASA - National Aeronautics and Space Administration

Navigation is a method used to learn exactly where airplanes, ships, or spacecraft are in the sky, on the ocean, or in space. Navigation also helps people get planes, ships, and spacecraft to where they need to go. Sometimes, navigation is also used on land -- by cars, for example. The person who does the navigating is called a navigator.

Image to left: Navigation tools, such as a sextant, help navigators see where their ship is. Credit: World Book illustration by Richard Hook

A navigator on a ship has several ways to find out where the ship is and where it is going.

Sometimes the navigator uses a method called dead reckoning. To use dead reckoning, the navigator must know exactly where the ship was at a certain time. The navigator then figures out how far and which way the ship has gone since that time. That tells the navigator where the ship is now. In piloting, the navigator uses a landmark, such as a buoy, to find out where the ship is. The buoy is marked on a special map called a chart. The navigator figures out how far the ship is from the buoy, and whether the ship is to the east, north, south, or west of the buoy. Using a chart and other tools, the navigator can then see exactly where the ship is.

Sometimes a navigator looks at the sky. The position of the stars, sun, and moon in the sky can tell the navigator where the ship is on the Earth. Navigators may also use radio signals, which are waves of power that people can't see; satellites, which are objects that people have put in space and which now travel around the Earth; computers; and other tools in their work.

Image to right: A navigator plots a vehicle's course and position on a chart that shows what the area looks like. Credit: U.S. Navy

Basic navigation tools include a chart and a compass. A compass shows which way is north, south, east, and west.

How to cite this article: To cite this article, World Book recommends the following format: "Navigation." The World Book Student Discovery Encyclopedia. Chicago: World Book, Inc., 2005.

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