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All shows at the Peter Harrison Planetarium today (Friday 22 February) are now sold out. The Royal Observatory is still open for all visitors. For Planetarium ticket holders: please ensure you arrive at least 15 minutes before the show as late entry is not permitted.
Stand on the historic Prime Meridian of the World at Royal Observatory Greenwich, the home of Greenwich Mean Time (GMT).
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.
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