A standard part of any international business, travel agent or globetrotter, time zone clocks are a series of clocks showing different times around the world, often but not always relating to cities at the epicentre of different time zones.

Whilst different areas have always had different set times, usually relating to sunrise and sunset, the first time zones came about when the world started getting a little smaller.

### The Birth Of Greenwich Mean Time

The birth of timezones begins with the birth of Greenwich Mean Time, which itself was meant to solve the problem of navigating at sea. Latitude could be calculated by measuring the sun at noon but longitude was more difficult.

The Royal Observatory in Greenwich, initially known as Flamsteed House and built on top of the ruins of Greenwich castle, was built in 1676 and was dedicated entirely to figuring out how to calculate longitude at sea.

John Flamsteed, the first Astronomer Royal, tirelessly worked on cataloguing the stars to create a chart that could be used at see to figure out the longitude of where ships were.

Two initial methods were found to figure out longitude, however using lunar distances required four hours of calculations initially and would take a long time to simplify the necessary calculations down to tables for the positions of the Sun, Moon and nine suitable stars every single day.

A chronometer, accurately set to the time of a known fixed location was another solution. As half a degree of longitude equalled about two minutes of time, if you simply looked at what time GMT was at noon local time, you could much more quickly calculate how many degrees of longitude you were away.

Time zones came about because 15 degrees of longitude equalled about 60 minutes of the time difference, and since the earliest calculations were relative to the Royal Observatory, Greenwich Mean Time has become the standard centre of time zones ever since, ratified in 1884.