Laser lights up London
sky
Thursday, 16 December, 1999, 21:35 GMT
A
laser has been beamed into the sky over London to show the path of
the Prime Meridian. The meridian marks the international timeline
and will become a centre of celebrations in the UK on the night of
31 December.
The Millennia Vs green laser was turned on at
the Royal Observatory Greenwich, which is sited in south east
London. 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.
Diode lasers are used to produce the beam which
will sweep out over the capital every evening.
The laser light is reflected off two mirrors and
comes out of a hole in the old observatory building.
The
light should be visible for more than 10 miles on a clear night,
more on a cloudy night when the lights reflect off dust and cloud
particles in the atmosphere.
The lasers, designed by US company Spectre
Physics, are suspended in the roof of the building, seven metres
above the precise location from where time was once measured.
Greenwich Mean Time (GMT) evolved as the world's
official time reference and served the purpose until 1972. But the
development of super-accurate atomic clocks saw the new Co-ordinated
Universal Time (UTC) adopted internationally from 1972.
Related Links:
The
Y2K Page
TOP
