Marking the international timeline, the Meridian line laser emitted from the Royal Observatory since 1999, cuts through the skies above London, United Kingdom. 9th December 2011
The iconic Prime Meridian Line laser, which has shone since 1999 at the Greenwich Observatory. The beam uses diaode lasers, designed by Spectra Physics and is visible for more than 10 miles (more on a clear night). The Royal Observatory in Greenwich is the home of the Greenwich Mean Time (GMT) and the Prime Meridian of the world. A laser has been beamed into the sky over London to show the path of the Prime Meridian. The meridian marks the international timeline. The path of the meridian runs in a circle through both poles and past the Millennium Dome, which has become a cultural icon for the year 2000. Greenwich was voted as the location for the Prime Meridian of the world - zero longitude and the basis of the International Time Zone system - by the International Meridian Conference in 1884.