Visit the Royal Observatory in Greenwich, London. Home of Greenwich Mean Time (GMT), the Prime Meridian of the world and London’s Planetarium.
Find out how the Royal Observatory became the home of Greenwich Mean Time (GMT) and the first state-funded scientific institution of its day. Stand on the historic Prime Meridian of the world, where East meets West, see John Harrison’s groundbreaking timekeepers up close, and explore the home of the Astronomer Royals.
The Prime Meridian Line
Stand on the historic Prime Meridian of the World at Royal Observatory Greenwich, the home of Greenwich Mean Time (GMT).
- 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).
- Tickets to the Meridian Line and Historic Royal Observatory also includes admission to our Time galleries and Great Equatorial Telescope.
- 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.
Since the late 19th century, the Prime Meridian at Greenwich has divided the eastern and western hemispheres of the earth – just as the equator divides the northern and southern hemispheres.
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. The cross-hairs in the eyepiece of the telescope precisely defined Longitude 0° for the world.
The Peter Harrison Planetarium
Take a tour of the universe from the comfort of your seat at London’s only planetarium.
- Discover the moons of the Solar System in this brand new show narrated by our Royal Observatory astronomers.
- Explore the night sky in this classic guide, presented in real-time.
- Ted’s Space Adventure – a special planetarium show for under-7s.
- Tour the Solar System and beyond, and meet our next-door neighbours in space!