#### How many different quantities can be used to locate a specific place on Earth?

Apart from latitudes and longitudes (both geographical and magnetic), is there another way of determining the position of an exact place on Earth?

Anonymous

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Mahesh Godavarti

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What you are asking about is are there other ways of defining a coordinate system that can be used to locate any point on the surface of the Earth.

Latitude and Longitude measures are defined by two angles. The longitudinal angle is the angle a vertical slice going through the point of interest makes with the vertical slice going through the Prime Meridian (i.e. through Greenwich, England). Therefore, by definition Greenwich, England has a longitudinal angle of 0 \degree . Longitudinal angles run from 180 \degree E to 180 \degree W.

The latitudinal angle is the angle made by the line joining the point of interest to the center of the earth with the horizontal slice going through the equator (that's why the poles have a latitudinal angle of 90 \degree and any point on equator has a latitudinal angle of 0 \degree . Latitudinal angles run from 90 \degree N to 90 \degree S.

A picture is worth a thousand words (source of the picture - http://geokov.com/education/latitude-longitude.aspx). So, here goes.

In the image \lambda is the longitudinal angle and \phi is the latitudinal angle.

These two angles uniquely define the point of interest and form the coordinate system that is in active use.

Longitude and Latitude are an example of a Geographical Coordinate System. There are many other Geographical Coordinate Systems. The most popular of them all is the UTM (Universal Transversal Mercator).

https://www.maptools.com/selecting_a_coordinate_system

Moreover, You can come with your own coordinate system. Here's one that I came up with. I will call the coordinates in this system - Longlatitude and Latitude. Latitude is the same as the latitude in the coordinate system we are familiar with. However, Longlatitude is defined in a similar way as Latitude where the Longlatitudinal circles run vertically (as opposed to latitudinal circles that run horizontally). I will arbitrarily define the vertical slice going through the center and Greenwich, England as my vertical slice of reference. The Longlatitudinal angle is the angle made by the line joining the point of interest to the center of the circle with the half of vertical slice passing through Greenwich and the latitudinal angle is the angle made by the same line with the horizontal slice.

In the new coordinate system, the longlatitudinal angle runs from 180\degree E to 180\degree W and the latitudinal angle runs the usual 90 \degree N to 90 \degree S.

Here is a picture the "new" longlatitudinal and latitudinal lines on the surface of a sphere.

Vivekanand Vellanki

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