Why do you have Greenwich mean time?

Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, England. It is the basis for the Coordinated Universal Time (UTC) standard, which is used as the civil time in most countries of the world.

There are a few reasons why GMT was chosen as the prime meridian for the world.

* Historical reasons: Greenwich was the site of the Royal Observatory, which was founded in 1675. The observatory played a leading role in the development of astronomy and navigation, and its meridian was used as the basis for calculating longitude.

* Scientific reasons: The meridian of Greenwich is close to the centre of the Earth's landmass, which makes it a convenient reference point for timekeeping.

* Political reasons: England was a major naval power in the 18th and 19th centuries, and the use of GMT as the standard time helped to facilitate trade and navigation.

GMT was officially adopted as the prime meridian by the International Meridian Conference in 1884. Since then, it has become the standard time for most of the world.