GMT - Greenwich Mean TimeGreenwich Time Meridians

Greenwich Time and World Countries and City Times

The above GMT map of Greenwich England show the history over the years of the starting meridian for time keeping. The yellow above meridian line is the Bradley Meridian defined by telescope observations. This was the first meridian line surveyed in on the first chart in 1738. The Bradley Merdian location 0° 00′ 05.33″ W is still used as the Zero longitude for British Ordnance Survey to this day. The upper red meridian line is the surveryed 1851 Airy Meridian defined by the Airy Transit Circle. The more accurate Airy Meridian was adoptedas the Prime Meridian in 1884 The location is farather to the east by about six meters 0° 00′ 05.3101″ W. The green Prime Meridian line is the current IERS Reference Meridian line based on the World Datum. The 0° 00′ 00.00″ location is the current line used for GPS usage around the World.

Facts about the Greenwich Time Prime Meridian.
Question: Who was behind the push for the Prime Meridian standardization of a zero longitude?

Answer: The man behind the push for a standard longitude time reference line is a Scottish immigrant living in Canada. His name was Sandford Fleming and he was a surveyor, Cartographer(mapmaker), and civil engineer who understood the need to standardize the Prime Meridian to just one international location.

Question: How and when was the Prime Meridian location decided?

Answer: In 1884 The U.S. president Chester A. Arthur sent out a invitation to forty-one delegates from twenty-one nations to meet in Washington, D.C. to decide on the location of the Prime Meridian to finally unify the World’s time and map surveying.
At the conference, they decided to divide the World into twenty-four time zones, with each being 15 degrees of longitude in width. Many famous landmarks were discussed as possible locations for the prime meridian. These included Alexandria, Egypt, The Great Pyramid, The Leaning Tower of Pisa, The Vatican, The Temple in Jerusalem and many other used prime meridians. However, the scientists and surveyors released that the location also needed a first-class astronomical observatory for astronomical time measurements. The Royal Observatory at Greenwich, England, was all ready a front running candidate for the Prime Meridian location. The main reason was that almost seventy-five percent of World ocean shipping used Greenwich time clocks to set their ships marine chronometers by. The only large countries to oppose the Greenwich location was France and Brazil and San Domingo(Dominican Republic), but the location was agreed on with a vote of 22-3.

Question: What countries, cities, features, and landmarks does the Greenwich Prime Meridian pass through?

Answer: To the south, the prime meridian first passes through the coastal town of Peacehaven, England, than goes through the English Channel, Le Havre,France, The Pyrenees in Spain, Algeria, Mali, Burkina Faso, Togo, Ghana, the South Atlantic Ocean, Southern Ocean, and the Antarctic. In the north, the prime meridian goes through the Thames River, Stratford, Somersham, Waltham Abbey, Holbeach, Boston, Louth, the North Sea, Norwegian Sea, Greenland Sea, and the Arctic.

Question: What is the highest location on the Prime Meridain time line?

Answer: The highest location is on the Spain-France border in the Pyrenees mountains. The elevation at the border where the time line crosses is 3037 meters.

Disclaimer: is not responsibly for any shown time errors or new UTC border changes not shown.
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