Put simply, Greenwich Mean Time is the annual average of the time when the sun crosses the Prime Meridian at the Royal Observatory, Greenwich, (it’s an average – that’s why it’s called ‘Mean’). Stand on the historic Prime Meridian of the World at Royal Observatory Greenwich, the home of Greenwich Mean Time (GMT). It was first established by Sir George Airy in 1851, and by 1884, over two-thirds of all ships and tonnage used it as the reference meridian on their charts and maps. This time zone is in use during standard time in: Europe, Africa, North America, Antarctica.. So the standardisation of time began in the 1840s. Look out for the green laser which marks the Meridian Line in the evening sky from the top of the hill in Greenwich Park towards the London Skyline. Available from our Online Shop, our exclusive replica Shepherd Wall Clock. It’s behind a black iron gate just next to the enclosed area where the long line is. The cross-hairs in the eyepiece of the telescope precisely defined Longitude 0° for the world. It was first put into place in December 1847 when the railways switched from local time to Greenwich Mean Time. In 1884 the Prime Meridian was defined by Transit Circle telescope at the Royal Observatory which was built by Sir George Biddell Airy, the 7th Astronomer Royal, in 1850. Grab an iconic selfie on the historic Prime Meridian Line of the world and share using #PrimeMeridian; Discover the remarkable story behind the reference line for Greenwich Mean Time (GMT). Home to the Meridian Line at the Royal Observatory, Cutty Sark, the National Maritime Museum, the Old Royal Naval College including the fabulous Painted Hall, London’s cable car, Greenwich Market, Greenwich Park and The O2 Arena. Tickets to the Meridian Line and Historic Royal Observatory also includes admission to our Time galleries and Great Equatorial Telescope. There’s lots more to see as well – the original building was designed by Christopher Wren and houses the UK’s largest refracting telescope and a fantastic collection of clocks, astronomical instruments and other exciting artefacts. Find out more about the historic Prime Meridian of the World, Share your best photos with us via Facebook, Instagram or Twitter. Find the perfect greenwich mean line stock photo. Insight Investment Astronomy Photographer of the Year, Illuminated Meridian Line at night, Royal Observatory, Greenwich. No need to register, buy now! Visit Greenwich and stand on the Prime Meridian, with a leg in each hemisphere, eastern and western, at the Royal Observatory.. Nowadays we all take it for granted that we can find out the right time wherever and whenever we are in the world. The rest of the country followed and we were all waking up to Greenwich Mean Time by 1865 or so. Discover the remarkable story behind the reference line for Greenwich Mean Time (GMT). This time zone is often called Greenwich Mean Time. Royal Observatory Greenwich Audio Guide Tour. All visitors will need to book a ticket in advance. Welcome to Greenwich. Greenwich Mean Time (GMT) has no offset from Coordinated Universal Time (UTC). Nowadays we all take it for granted that we can find out the right time wherever and whenever we are in the world. Longitude found - the story of Harrison's Clocks, Grab an iconic selfie on the historic Prime Meridian Line of the world and share using #PrimeMeridian. Local time was defined, generally, by the sun and could vary widely across the UK, which was a major headache for the expanding railway industry. Huge collection, amazing choice, 100+ million high quality, affordable RF and RM images. Before the mid 1850s it might be 2.30 in the afternoon where you were and 3.00 in the afternoon ten miles down the road! Log in, get borders of adventure updates by email, Visit the Greenwich Meridian Line in London – Time Travel in the City. Coordinates. Visit Greenwich and stand on the Prime Meridian, with a leg in each hemisphere, eastern and western, at the Royal Observatory.