Year of 2018

Hello from zero degrees longitude

This laser projected from the Royal Observatory at Greenwich, in London, England, marks the prime meridian, dividing Earth’s Eastern and Western Hemispheres and helping travelers to chart their courses by establishing a universally adopted zero degrees longitude. The meridian itself is essentially an imaginary line, arbitrarily placed. By the early 19th century, most maritime countries had established their own prime meridians to aid in navigation. But on this date in 1884, delegates from 25 nations met at a conference in Washington, DC, where they established Greenwich as the international standard for mapping and timekeeping. The decision made sense, as the Greenwich meridian was already widely used. But there was one holdout: France abstained from the vote and used its own Paris meridian for several decades before eventually joining other countries in recognizing the Greenwich meridian.

A prime meridian, based at the Royal Observatory, Greenwich, in London, England, was established by Sir George Airy in 1851. By 1884, over two-thirds of all ships and tonnage used it as the reference meridian on their charts and maps. In October of that year, at the behest of US President Chester A. Arthur, 41 delegates from 25 nations met in Washington, D.C., United States, for the International Meridian Conference. This conference selected the meridian passing through Greenwich as the official prime meridian due to its popularity. However, France abstained from the vote, and French maps continued to use the Paris meridian for several decades. In the 18th century, London lexicographer Malachy Postlethwayt published his African maps showing the "Meridian of London" intersecting the Equator a few degrees west of the later meridian and Accra, Ghana.