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The original literal meaning of the word “orientation” was “To face east.” East, because that’s the direction from which the sun rises. Before the compass, humans were, for the most part, unaware of a North and South Pole, not to mention pole magnetism. Therefore, the sun was a fundamental reference point. Of course, today we have many tools available to help us determine our orientation, the compass being the primary tool for use under water.

The basis of compass navigation is formed by the four cardinal points. No matter where you are in the world, the cardinal points remain the same: North, East, South and West. Each of these points is subdivided further into intermediate points.

Meridians and Parallels

Early travelers and navigators needed a way to identify their location and the direction that they were facing at any given moment. To assist with this endeavor, they divided the Earth into segments by establishing imaginary lines. These lines are still in use today, and form the foundation of global navigation.

There are 180 lines, or vertical circumferences that run vertically from the North Pole to the South Pole called Meridians. Meridians are technically all the same length; one does not stand out from the other. As such, the Greenwich Meridian named for the district in London that the meridian crosses, was chosen as a reference meridian. For navigational purposes, any location referenced is said to be either East or West of Greenwich. Standard global time is also typically referenced as Greenwich time.

There are 180 horizontal circumferences that run parallel to each other, aptly named Parallels. The parallel with the greatest circumference — called the Equator, divides the planet in half. The two hemispheres that are above and below the Equator are called the Northern (Boreal) Hemisphere and the Southern (Austral) Hemisphere, respectively.

As an object moves away from the equator, the parallels become smaller until they are reduced to a point at each pole.

Latitude and longitude

Together, the Meridians and Parallels create a global, sphere shaped grid.

In order to locate a specific point on the grid, one must be able to define the Latitude; the angular distance north, or south of the Equator (zero degrees latitude), and the Longitude; the angular distance east or west of the Greenwich Meridian (zero degrees longitude) of the point desired.

Before modern navigation systems and global satellite positioning, early explorers had to use basic tools in combination with celestial objects to derive latitude and longitude. The compass, in conjunction with a sextant and a chronometer (a very precise clock) were typically used to measure a set of data points, which when compared to celestial charts, would indicate the precise position from where the measurements were taken. 

Today, most non-military navigation above the surface is conducted almost instantaneously by way of satellite positioning systems.

Commercial systems available to the public include GPS and GLONASS, among others, which is now available even on smartphones and they function instantly. When we ask the different map applications “where we are” or we send our friends “the location point in an App” we use the internal GPS of our smartphone to send our geographical coordinates.


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