Tech History Today
October 13, 1884: Greenwich gets adopted as the Prime Meridian
Today in 1884, Geographers and astronomers adopted Greenwich as the Prime Meridian, making it the International standard for zero degrees longitude.
As the United Kingdom grew into an advanced maritime nation, British mariners kept at least one chronometer on GMT to calculate their longitude from the Greenwich meridian, which was by convention considered to have longitude zero degrees. It was internationally adopted at the International Meridian Conference of 1884 by shooting a laser northwards at night to indicate the meridian.