The Greenwich Royal Observatory - Timekeeper to the world

The Greenwich Royal Observatory
Timekeeper to the world

-- Friday' News Paper

Compiled by David A. Perera
during his recent visit to Lonodon

Greenwich is a lovely peaceful village about 15 miles from Central London on the south bank of the River Thames. The village is famous for the buildings of the National Maritime Museum, the Royal Naval Academy and the Royal Observatory sitting on a beautiful hilltop in Greenwich.

The observatory building was built by the great British architect of the 17th century, Sir Christopher Wren in 1675. Parts of the old observatory are now a museum and called the Flamsteed House.

Thousands of visitors who arrive at the Greenwich observatory can see the big clock-face showing the Greenwich Mean Time (GMT) and the Greenwich meridian marked on the ground from which the longitude is measured.
The Flamsteed House has now put up a millennium e-clock showing the time, date and year with an accuracy of a millionth of a second.

What is a Meridian?
A meridian is an arbitrary north/south line chosen by an astronomer. With a telescope or quadrant positioned on a meridian, the astronomer can measure the exact moment the stars and planets cross, or transit the sight of the instrument.

By comparing thousands of observations taken from the same meridian, it is possible to build up an accurate map of the night sky. In the past many meridians have been used by astronomers, Greenwich was recognised as the home of the Prime Meridian, or Longitude 00 in 1884.

Centre of Transit
Circle
Latitude: 51” 28’ 38” North
Longitude: 0” 00’ 00”

Courtesy: Encyclopaedia Britannica

A view of Central London (background) and the Maritime/Naval buildings from Greenwich	Reflector 40’, the largest telescope at the time

GMT clock and British units of length and weight specimens	Edmond Halley (1650-1742 AD)

Edmond Halley’s Tombstone:
The Latin Inscription reads:
“Beneath this gravestone, Edmond Halley, unquestionably the most eminent of the astronomers of his age rests peacefully with his dearest wife so that the reader may know what kind and how a great man [Halley] was, read his various writings in which he dignified, embellished and strengthened almost all the arts and sciences.
And, therefore, as he was a man so greatly cherished by his fellow-citizens during his lifetime, so let a grateful posterity venerate his memory. Born in the year of our Lord 1656. Died 1741/2. This stone was consecrated to excellent parents by to devoted daughters in the year 1742.”