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GREENWICH ROYAL OBSERVATORY. A TOP MUSEUM IN LONDON.
THE PRIME MERIDIAN
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The Greenwich Royal Observatory, Greenwich England, is the home of Greenwich Mean Time and the Prime Meridian of the World, which makes it the official starting point for each new day and year.
The Observatory, with the Queens House Greenwich, are both incorporated within the National Maritime Museum to form one of the top Museums in London. It is also a World Heritage Site.
It is the oldest scientific institution in Britain and was the pioneer in navigation, accurate timekeeping, determination of the accurate positions of stars and The Nautical Almanac Publication.
The publication of The Nautical Almanac in 1767 based on the time at the longitude of Greenwich, was a great leap forward and a major aid to ship's navigators.
It played a major part in the decision taken in 1884 to make the Greenwich Meridian the Earth's Prime Meridian and the position where the international time zones begin.
Situated as it is on top of Castle Hill in Greenwich Park, Greenwich Royal Observatory gives magnificent views, overlooking London and the River Thames.
If you are approaching it from the centre of Greenwich, prepare yourself for quite a steep climb. The climb however, is well worth the effort when you arrive at the top.
In May 2007 a major capital project, "Time and Space", opened up the entire Greenwich Royal Observatory site for the benefit of visitors.
The £16 million transformation features three new modern astronomy galleries, four new time galleries, facilities for collections, conservation and research, a learning centre and the 120-seat planetarium, Peter Harrison Planetarium (named after it's major donor, Peter Harrison) designed to introduce the world beyond the night sky. It is London's only planetarium.
The Greenwich Royal Observatory is also the home of the Harrison timekeepers. These are marine clocks (or chronometers), which were invented and developed by John Harrison in what was deemed an insoluble problem of determining longitude at sea.
The likes of such eminent scientists, Sir Isaac Newton, the English physicist, mathematician, astronomer and natural philosopher and Christiaan Huygens, the Dutch mathematiciam, astronomer, physicist and horologist doubted that a clock with these capabilities could ever be built. After a lifetime of dedicated work, Harrison proved them all wrong.
The longitude watches (chronometers) H1, H2, H3 and H4 are at the observatory, H5 is owned by the Worshipful Company of Clockmakers and can be viewed at the Clockmakers Museum in the Guildhall, London).
The marine chronometers which were subsequently made after Harrison's innovative work, were based upon his original ideas and were a vital part of every ship's toolkit up to the 1970s, when Global Navigation Satellite Systems took over.
The Greenwich Royal Observatory also has a twenty eight inch refracting telescope, which is the largest in the U.K. and the seventh largest in the world. It was retired from active service in the late 1960s and is now part of the educational programmes they run there.
What to see there: Flamsteed House and Astronomer's Apartments.Flamsteed House, which was designed by Sir Christopher Wren in 1675 on the instructions of King Charles II is the original Observatory and occupies the site of Greenwich Castle.
The castle was later used as a guest house and hunting lodge by King Henry VIII. It was demolished to make way for the construction of the Royal Observatory in 1675, but the hill on which it stands still bears testimony to it's presence by it's name, Castle Hill.
See the most important time piece ever made in the Time and Longitude Gallery.
It is the H4 which solved the previously thought insoluble problem of knowing exactly where a ship was at sea saving many lives. It eventually won it's designer John Harrison the Longitude Prize.
Astronomers Royal Apartments:These are the apartments where successive Astronomers Royal actually lived and worked.
The role of Astronomer Royal was created by King Charles II when John Famsteed was appointed by royal warrant to be 'The King's Astronomical Observator'.
He was instructed to apply himself with the most exact care and diligence to the rectifying the tables of the motions of the heavens, and the places of the fixed stars so as to find out the so-much desired longitude of places for the perfecting the art of navigation.
In other words he was instructed to draw up a map of the heavens, accurate enough to be relied upon for navigation
He lived in the apartments from July 1676 until he was appointed priest to the parish of Burstow in Surrey in 1684. He held both positions as Priest and Astronomer Royal until his death in 1719.
Since Flamsteed there have been fourteen Astronomers Royal, at the Greenwich Royal Observatory, including Edmund Halley, all of whom have contributed so much to the field of astronomy and the understanding of the heavens.
The Octagon Room.This room was designed to observe eclipses, comets and the movements of the planets. It is open to the public and exhibits timepieces and astronomical instruments.
The Time Ball.First used in 1833, it was one of the world's earliest public time signals if not the earliest, informing ships passing along the River Thames below what time of the day it was.
Just once a day every day, at exactly 12.55, the red time ball ascends half way up the mast. With two minutes to go at precisely 12.58 it completes its journey to the top of the mast, where at precisely 13.00 the ball falls, providing the signal to everyone of the time of day.
The Meridian Gallery.
Camera Obscura.It is London's only public camera obscura and is located in a small building in the courtyard next to Flamsteed House. It uses a lens and rotating mirror to project a real-time moving panorama of Greenwich and the River Thames onto a circular table.
There have been several camera obscuras at Greenwich Royal Observatory since the first Astronomer Royal John Flamsteed used one, with which he was able to make his safe observations of the sun.
Standing in a darkened room with a pinhole or small aperture in one wall an upside-down image of the outside world will appear on the opposite wall. It is the forerunner of the modern camera.
The Prime Meridian Line.The Greenwich Royal Observatory, is the home of Greenwich Mean Time (GMT) and the Prime Meridian of the world.
A meridian is an imaginary line joining the north and south poles at right angles to the equator. The Prime Meridian is the meridian with a longitude of 0°, adopted officially in 1884 as a reference line from which longitude east and west are measured and as a basis for standardized time zones.
It was defined by the position of the large "Transit Circle" telescope in the Observatory's Meridian Building. The transit circle was built by Sir George Biddell Airy, the 7th Astronomer Royal, in 1850.
The cross-hairs in the eyepiece of the Transit Circle precisely defined Longitude 0° for the world. As the earth’s crust is moving very slightly all the time the exact position of the Prime Meridian is now moving very slightly too, but the original reference for the prime meridian of the world remains the Airy Transit Circle in the Greenwich Royal Observatory, even if the exact location of the line may move to either side of Airy’s meridian.
It passes through Greenwich, England, the site of the Greenwich Royal Observatory, which was founded in 1675 and which closed except as a museum in 1998.
The prime meridian, together with its opposite meridian having a longitude of 180°, divide the Earth roughly into the Eastern and Western Hemispheres, with those portions of the British Isles, Europe, and Africa that lie west of the prime meridian, considered for practical purposes as belonging to the Eastern Hemisphere.
