London - Greenwich Flamsteed House Observatory 70s mini

Postcard

 

• Picture / Image:  Flamsteed House, Greenwich at the observatory. Yellow mini parked outside!
• Publisher:  Colourmaster International
• Postally used:  no
• Stamp:  n/a
• Postmark(s):  n/a
• Sent to:  n/a
• Notes & Key words: 

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Postage & Packing:

UK (incl. IOM, CI & BFPO): 99p

Europe: £1.60

Rest of world (inc. USA etc): £2.75

No additional charges for more than one postcard. You can buy as many postcards from me as you like and you will just pay the fee above once. (If buying postcards with other things such as books, please contact or wait for invoice before paying).

Payment Methods:

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NOTE: All postcards are sent in brand new stiffened envelopes which I have bought for the task. These are specially made to protect postcards and you may be able to re-use them. In addition there are other costs to sending so the above charge is not just for the stamp!

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Text from the free encyclopedia WIKIPEDIA may appear below to give a little background information:

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The Royal Observatory, Greenwich (formerly the Royal Greenwich Observatory or RGO) was commissioned in 1675 by King Charles II, with the foundation stone being laid on 10 August.^[1] At this time the king also created the position of Astronomer Royal (initially filled by John Flamsteed), to serve as the director of the observatory and to "apply himself with the most exact care and diligence to the rectifying of 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 of the art of navigation." It is situated on a hill in Greenwich Park in Greenwich, London, overlooking the River Thames.

There had been significant buildings on this land since the reign of Edward I.^[2] Greenwich Palace, next to the site of the present-day Observatory was the birthplace of Henry VIII and the Tudors used Greenwich Castle, which was built on the land that the Observatory now stands on. Greenwich Castle was apparently a favourite place for Henry VIII to house his mistresses, so that he could easily travel from the Palace to see them.^[3]

The establishment of a Royal Observatory was proposed in 1674 by Sir Jonas Moore who, in his role as Surveyor General at the Ordnance Office, persuaded King Charles II that the Observatory might be built with Flamsteed employed in it.^[4] The Ordnance Office was given responsibility for building the Observatory, with Moore providing the key instruments and equipment for the observatory at his own personal cost. Flamsteed House, the original part of the Observatory, was designed by Sir Christopher Wren probably with the assistance of Robert Hooke and was the first purpose-built scientific research facility in Britain. It was built for a cost of £520 (£20 over budget) out of largely recycled materials on the foundations of Duke Humphrey's Tower, which resulted in the alignment being 13 degrees away from true North, somewhat to Flamsteed's chagrin.

It not only housed the scientific instruments to be used by Flamsteed in his work on stellar tables, but over time also incorporated a number of additional responsibilities such as the keeping of time and later Her Majesty's Nautical Almanac Office.

Moore donated two clocks, built by Thomas Tompion, which were installed in the 20 foot high Octagon Room, the principal room of the building. They were of unusual design, each with a pendulum 13 feet (3.96 metres) in length mounted above the clock face, giving a period of four seconds and an accuracy, then unparalleled, of seven seconds per day.

British astronomers have long used the Royal Observatory as a basis for measurement: four separate meridians have been drawn through the building. The basis of longitude, the Prime Meridian, established in 1851 and adopted at an international conference in 1884, passes through the Airy transit circle of the observatory. It was long marked by a brass strip in the courtyard, now upgraded to stainless steel, and, since 16 December 1999, has been marked by a powerful green laser shining north across the London night sky.

This old astronomical prime meridian has been replaced by a more modern prime meridian. When Greenwich was an active observatory, geographical coordinates were referred to a local oblate spheroid called a datum, whose surface closely matched local mean sea level, called the geoid. Several datums were in use around the world, all using different spheroids, because mean sea level undulates by as much as 100 metres worldwide. Modern geodetic reference systems, such as the World Geodetic System and the International Terrestrial Reference Frame, use a single Earth-centered oblate spheroid. The shift from several spheroids to one worldwide spheroid caused all geographical coordinates to shift by many metres, sometimes as much as several hundred metres. The Prime Meridian of these modern reference systems is 102.5 metres east of the Greenwich astronomical meridian represented by the stainless steel strip. Thus the strip is now 5.31 arcseconds West.

Greenwich Mean Time (GMT) was at one time based on the time observations made at Greenwich (until 1954). Thereafter, GMT was calculated from observations made at other observatories which were still active. GMT is now often called Universal Time, which is now calculated from observations of extra-galactic radio sources, and then converted into several forms, including UT0 (UT at the remote observatory), UT1 (UT corrected for polar motion), and UTC (UT in discrete SI seconds within 0.9 s of UT1). To help others synchronize their clocks to GMT, a time ball was installed by Astronomer Royal John Pond in 1833. It still drops daily to mark the exact moment of 1 p.m. (13:00) year round (GMT during winter and BST during summer).^[5]