Ticketed Free entry for members

Essential Information

Location
Royal Observatory
Price Included with entry to the Observatory

Stand on the historic Prime Meridian of the World at Royal Observatory Greenwich, the home of Greenwich Mean Time (GMT).

  • Grab an iconic selfie and share using #PrimeMeridian
  • Discover the remarkable story behind the reference line for Greenwich Mean Time (GMT)
  • Visit the Historic Royal Observatory, 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.

Find out more

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Why is the Prime Meridian in Greenwich?

When it came to choosing the Prime Meridian of the world, a contributing factor to Greenwich being chosen was that the USA had already chosen Greenwich as its own national time zone system.

As well as this, in the 19th century 72% of the worlds commerce depended on sea charts which used Greenwich as the Prime Meridian. 

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What is a Prime Meridian?

A meridian is a north-south line, selected as the zero reference line for astronomical observations. By comparing thousands of observations taken from the same meridian it's possible to build up an accurate map of the sky.

#PrimeMeridian

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Learn more at the Royal Observatory

Visit the home of Greenwich Mean Time (GMT), the Prime Meridian of the world and London’s Planetarium.

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A father and son play on the Prime Meridian Line outside the historic Flamsteed House building of the Royal Observatory

Royal Observatory

  • Royal Observatory
  • Meridian Line
  • Free Museums
  • Planetarium Shows
  • Cutty Sark
Adult £16
Child £8
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A brother and sister with their back to the camera look out from the viewpoint at the top of Greenwich Park towards historic Greenwich

Royal Museums Greenwich Day Pass

  • Two sites, one ticket
  • Cutty Sark
  • Royal Observatory
  • Guaranteed entry time
Adult £25
Child £12.50
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Member tickets

  • Free entry
  • Priority booking
  • Membership card number required
Members go free
Advance booking essential
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National Maritime Museum

Become a Member

  • Unlimited entry all year
  • Royal Observatory
  • Cutty Sark
  • Planetarium Shows
  • Special exhibitions
Direct Debit One-off
Individual: £50 Individual: £60
Family: from £65 Family: from £75
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