Nought Longitude

Where is nought longitude?

Nought degrees longitude passes through Greenwich on the River Thames in London, England. 0° longitude is known as the “prime meridian”. You can see at Greenwich the prime meridian mark from which all countries have reckoned longitude since 1884.

Longitude and latitude are fixed lines crossing the globe by which the location of any place on the earth’s surface can be determined and described.

Lines of longitude go from north to south. All start at the North Pole and end at the South Pole. Longitude is measured both 180° east  and 180° west of the meridian, the two together making the full 360° of the earth’s circumference.

World time is also measured from Greenwich. Greenwich Mean Time is zero hour and, depending on whether you are west or east of the prime meridian, you are either so many hours behind or ahead of the time of Greenwich.

The Royal Observatory at Greenwich was founded in 1675 and was one of Sir Christopher Wren’s great designs. In 1960 the building was opened as an astronomical museum.