The Center of Time: The Story of the Greenwich Observatory

If you have ever wondered why "GMT" (Greenwich Mean Time) is the baseline for global timekeeping, the answer lies on a hill in southeast London. The Royal Observatory in Greenwich is quite literally the center of world time and space.

The Crisis of Navigation

In 1675, King Charles II commissioned the observatory for a very practical reason: sailing. British sailors were dominating the seas, but they had a deadly problem. While they could calculate latitude (north/south) by looking at the sun, calculating longitude (east/west) was incredibly difficult. Ships were getting lost and crashing into rocks. The King ordered his astronomers to map the stars with unprecedented accuracy so sailors could use the night sky to navigate.

Winning the Global Standard

By the 1800s, Britain was the preeminent maritime power, and their star charts—based on the Greenwich meridian—were the most widely used in the world. In 1884, at the International Meridian Conference in Washington D.C., 25 nations met to establish a single "Prime Meridian" (longitude 0°) to standardize global mapping and time zones.

Because the majority of global shipping was already relying on British charts based on Greenwich, it simply made practical sense to officially crown Greenwich as the starting point for the world's time. From that moment on, every clock on Earth was set relative to the time on that hill in London.