Greenwich and the Prime Meridian

The globe is divided into a graticule

Who hasn't looked for a location in grid B7 on a map?

• Just as maps are divided into a grid in order to find geographic things quickly and efficiently, the earth is also divided into a graticule. This looks a little different, however, because the earth is a sphere and not a surface.
• Similar to dividing an apple into oblong slices and / or horizontal slices, the surface of the earth is divided into degrees of longitude and latitude.
• The longitudes, also called meridians, can therefore be imagined as circles on the earth's surface, all of which go through both the north and south poles. The specification 45 ° West therefore represents an east-west position on earth.
• The circles of latitude are parallel to the equator. The indication 15 ° North therefore indicates a north-south position on earth.
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Longitude and latitude - the earth's coordinate system simply explained

Longitudes and latitudes are used for orientation on the earth's surface. While …

• However, only both details, i.e. the length and width details, make it possible to determine the exact position on the earth's surface, for example that of a ship.

The prime meridian is in Greenwich

• Much of the earthly graticule is historical root, as well as the zero position of both latitude and longitude as well as the division into degrees.
• The 0. Accordingly, latitude is the equator, up to the North Pole values ​​up to + 90 °, up to the South Pole up to -90 °. Also the term "northern" resp. "southern" latitude is common.
• The longitudes are also measured in degrees.
• For the degrees of longitude there is no natural zero line like the equator, as is the case with the degrees of latitude. So you have to rely on choosing a certain meridian as the prime meridian.
• This 0. Longitude runs through Greenwich near London for historical reasons. This is a defined, but in principle arbitrary definition that was made in 1884 at an international conference in Paris. The term Greenwich Meridian is also common.
• At that time there was an important telescope in Greenwich, the central axis of which served as a fixation (now the Royal Greenwich Observatory). But this agreement certainly had something to do with the importance of England as a maritime nation.
• Counting from the prime meridian to both sides is up to 180 °, i.e. an eastern and western longitude are defined. The 180 ° meridian runs through the Fiji archipelago and passes New Zealand to the east. This meridian is followed (roughly) by the date line.