Royal Greenwich Observatory

The Royal Observatory in Greenwich, is a building located in the district of Greenwich in London. Today, it houses a museum of astronomical and navigational tools, which belongs to the National Maritime Museum.

The building was constructed in 1675 during the reign of Charles II of England and was used to make observations of the position of stars in the sky and thus improve the navigation. To make this possible two gigantic telescopes were installed in the observatory. Moreover, the king created a new position of Astronomer Royal to serve as the director of the observatory.

In 1884 an international commission responsible for the measurement of time established the position of the observatory as the starting point of all terrestrial meridians, settling in this place the 'Meridian' or 'Meridian' (0 ° longitude ), which is currently used to mark time zones around the world an is marked by the letters GMT (Greenwich Mean Time). To help synchronize other clocks to GMT, a time ball was installed by Astronomer Royal John Pond in 1833 which drops every day year round to mark the exact moment of 1 p.m.

Due to the increase in air pollution in London in the mid-twentieth century the observatory was relocated to Herstmonceux. That is why today the building in Greenwich serves only as a reference meridian and contains modern chronometers and laser sensors.

In 1997, the Royal Observatory in Greenwich was listed as a World Heritage Site by UNESCO.