• Short Summary

    The Royal Observatory, the oldest scientific establishment in Great Britain, was founded by Charles II in 1675 for the purpose of aiding navigation.

  • Description

    The Royal Observatory, the oldest scientific establishment in Great Britain, was founded by Charles II in 1675 for the purpose of aiding navigation. The first step towards finding longitude at sea was the compilation of a star catalogue and tables of the motions of the Sun, Moon and planets. To this end John Flamsteed (1646-1719) was appointed the first Astronomer Royal. Despite his small salary he provided most of the Observatory's instruments; with an equatorial sextant and a mural arc he made some 30,000 observations which were published posthumously in 1725 under the title "Historia Coolestis". This formed the foundation of modern astronomy.

    Flamsteed's immediate successors, Edmond Halley (1656-1742) and James Bradley (1697-1762) added to the Observatory's buildings and instruments. Although best known as the first man to compute a cometary orbit, Halley's greatest contribution to knowledge was his assistance in publishing Newton's "Principia" in 1687. Bradley's achievements included the discovery of the aberration of light and nutation, while his observations remain the earliest of use to astronomers today.

    A solution to the longitude problem was obtained in 1765 when John Harrison won the GBP20,000 prize offered by the Government with his marine chronometer which, coupled with the invention of the sextant, made it possible to determine a ship's position with the aid of an almanac and of a fundamental standard of Universal Time, both provided by astronomical observations.

    There remained, however, another method, that of lunar distances, which required an accurate almanac giving the Moon's place and those of certain fixed stars.

    The next Astronomer Royal, Nevil Maskelyne (1732-1811), pressed the Government to authorize such an ephemeris and the first Nautical Almanac appeared for the year 1767.

    John Pond (1767-1836) undertook the trial of chronometers offered to the Government (as the Observatory had come under Admiralty control in 1818) and erected the Greenwich Time Ball in 1833. This was the first regular public time signal in the world. Subsequently, as a result of Pond's ill health and difficulties with his assistants, the Nautical Almanac was taken out of his hands and he resigned in 1835.

    This state of affairs necessitated the appointment of a strong personality and consequently George Biddell Airy (1801-92), the last Astronomer Royal to be appointed by Royal warrant, set about putting the Royal Observatory on a business footing. During his long and strict term of office the establishment underwent a period of expansion.

    The addition of the Meteorological and Magnetic Department in 1840, the extension of buildings and erection of the famous Transit Circle (with which some 700,000 observations were made) in 1851,the Great Equatorial in 1858 and the Solar Department in 1873 were among the results of his tireless energy. His attention to fundamental, or positional, astronomy, with the foundations laid by his predecessors, led Simon Newcomb, the American astronomer, to state "that if this branch of astronomy were entirely last, it could be reconstructed from the Greenwich observations alone."
    Honoured by his own country and the world, Sir George Airy retired in 1881 and was succeeded by William M.H. Christie (1945-1922) and in 1884 Greenwich was chosen as the Prime Meridian at a conference in Washington.

    Astronomy was revolutionised during the latter half of the nineteenth century, by three developments: the invention of photography, the development of stellar spectroscopy, and the construction of the great 60-inch reflecting telescope (followed later by the 100-inch and 200-inch telescopes) in California. At Greenwich, the 26-inch refractor (still used for the determination of stellar parallaxes by photography), the 28-inch refractor (used for visual observations of double stars), the 13-inch Astrographic refractor (used for the photographic determination of proper motions), and the 30-inch reflector were all introduced in this period.

    Frank W. Dyson (1865-1937) was appointed Astronomer Royal on Sir William Christie's retirement in 1910 and introduced free pendulum clocks into the Time Department. Although Greenwich had sent out time signals via the railway telegraphs as early as 1883, the inauguration of the "6 pips" in 1924 brought accurate time to millions through the medium of radio. Three years later a similar aid to navigation was introduced by rhythmic time signals sent out twice daily from Rugby. Dyson's term of office was also noted for the famous eclipse expedition of 1919 in which A.S. Eddington and others verified Einstein's prediction of the deflection of light rays by the sun, and for the important contributions to astrophysics made by further Greenwich eclipse expeditions and by the work on stellar colour temperatures carried out with the 30-inch reflector by W.M.H. Greaves.

    Before the end of Sir Frank Dyson's term of office two important instruments were planned, the 36-inch Yapp reflector, equipped with a slit spectrograph, and the Reversible Transit Circle.

    Shortly after Harold Spencer Jones became Astronomer Royal in 1933 these instruments were brought into use, followed by quartz clocks, the daily rates of which are in the order of only a few thousandths of a second a day. From 1936 the Royal Observatory automatically controlled the Post Office "Speaking Clock" (TIM).

    During the following year the Nautical Almanac Office was again placed under the Astronomer Royal's control and shortly afterwards issued the Air Almanac as an aid to air navigation.

    During the World War II the Observatory was dispersed for safety, the Meteorological, Solar and Astrometric Departments alone remaining at Greenwich. During this period the buildings and some instruments suffered considerable damage.

    Negotiations had meanwhile been going on about the removal of the establishment to a more favourable site away from the London fog and smoke, and in 1946 it was announced that the Observatory's new home would be Herstmoncoux Castle and that it would be renamed by Royal Assent the Royal Greenwich Observatory.

    The removal began in 1948 and the first observation was taken at Herstmonceux by the Solar Department on May 2, 1949. The construction of large buildings and the erection of telescopes being a long an costly business, it was not until 1955 that a stellar observation was made by the new Photographic Zenith Tube.

    By now the Royal Observatory at Greenwich had been transferred to the care of the National Maritime Museum, the reconditioned Octagon Room, Flamsteed's original observatory, being opened as a Museum of astronomy and Navigation on May 8, 1955, by H.R.H. The Duke of Edinburgh.

    Sir Harold Spencer Jones retired at the end of 1955 and was succeeded by Dr. Richard v.d.R. Woolley, the eleventh Astronomer Royal.

    By 1957 the Reversible Transit Circle was in operation and the large West Building completed. The latter contains the Nautical Almanac Office, several astronomical departments, and the Chronometer and Engineering Workshops.

    The autumn of 1958 saw the completion of the Equatorial Group, housing the 26- and 28-inch astrographic refractors and the 30- and 36-inch reflectors.

    When funds become available, it is planned to add to these a 98-inch reflector (the Isaac Newton Telescope) and a Schmidt telescope, both of which will serve to analyse the light emitted by faint stars in order to find out more about their motions and physical properties.

    The Royal Greenwich Observatory, with its new and remounted instruments and a staff of more than a hundred, is now in a position to resume full-scale programmes in fundamental astronomy and attack the problems of astrophysics.

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