Way back in the Third Century B.C.E., the Greek mathematician and geographer Eratosthenes proposed lines running north to south and east to west as a way of precisely locating where one is on the earth.

A hundred years or so later, Hipparchus, another Greek mathematician and astronomer took Eratosthenes work a step further. He was the first to call Eratothenes’ grid, latitude and longitude and created trigonometry as a way to measure the orbits of the sun and the moon. His long list of other mathematical “inventions” and his lunar and solar theories led to his being inducted to the International Space Hall of Fame in 2004.

Latitude are imaginary circles that run horizontally around the world. Zero latitude is the equator. The father north or south from the Equator, the higher one’s latitude.  The letter N or S is used to designate north or south latitudes, i.e. 18 degrees, 15 minutes, 32 seconds North (18o, 15’, 32”N).

The imaginary lines that run north and south are known as longitude. For example, go east toward France from Great Britain and the digits are followed by the letter E for East. Go west into the Atlantic and it is referred to as West longitude. East or West longitude increases to 180 degrees that is the International Date Line.

Today, the Prime Meridian, or zero degrees longitude runs through the Royal Observatory in Greenwich in the U.K. However, it wasn’t always the Prime Meridian.

As the dominant sea power and sea faring nation, the Brits created the Royal Observatory in 1851 and declared the Prime Meridian ran through the observatory’s grounds. Up until this point, there was no standard and many countries claimed that zero longitude ran through their country.

By the late 1880s, two thirds of the worlds ship captains and owners used the British base prime meridian as the standard. In 1884, U.S. President Chester A. Arthur convened the International Meridian Conference that designated the Prime Meridian or Zero Longitude to be the one that ran through the Royal Observatory. It took until 1911 before the French gave up their claim that the Prime Meridian ran through Paris.

Another 19th Century invention, the railroad led to another innovation, Greenwich Mean Time. Trains ran on regular schedules that were measured in hours and minutes, not days, weeks or months. Countries were struggling with timetables, i.e. noon in London wasn’t always the same as noon in Manchester. In the U.S. there were over 100 standards that varied b as much as three hours.

The size of North America led a Canadian by the name of Sir Stanford Fleming to propose time zones. His worldwide system was adopted by most U.S. railroads in 1883 and another output of the International Meridian Conference was the adoption of 24 time zones around the world.

By 1895, most of the U.S. states had adopted the time zone concept. However, it took the Standard Time Zone Act of 1918 to require all states to adopt the time zones we know to day. By 1929, all the countries in the world adopted Fleming’s system.