And this is what the Royal Observatory was founded to do. It was not until the invention of the telescope, the pendulum clock, the micrometer screw and logarithms in the seventeenth century that astronomers became equipped with the tools they needed in order to begin to turn Werner’s idea into a practical reality. At that time however, star charts were too inaccurate and the precise motion of the Moon and the effects of refraction by the Earth’s atmosphere too poorly understood for the method to be practicable. As early as 1514, Johann Werner of Nuremberg had suggested using the Moon as an astronomical clock. The improvements that came with the invention of the pendulum clock in 1657 were substantial and revolutionised astronomy, but on board a moving ship, a pendulum would beat irregularly and occasionally stop beating altogether.Įvery hour, the Moon moves by about its own diameter against the background of stars. The idea of taking a clock to sea had been considered, but even the best were far too inaccurate to be of use. In theory then, in order to find out how far east or west he was from his homeland, all a sailor had to do was determine his local time from observations of the Sun or stars and compare it with the time back home at the same moment. The maritime nations of Europe offered a variety of large rewards or prizes for a solution.Įach 15° of longitude is equivalent to a difference in time of one hour. As trade routes opened up, it became increasingly urgent to find a solution to the so-called longitude problem.
Those in Cambridge have been absorbed by the University.īack in 1675, although a sailor was able to measure his latitude – how far north or south he was – once out of sight of land, he had no means of measuring his longitude or how far east or west he was. Some at Herstmonceux are in use as a Science Centre, whilst others are occupied by the International Study Centre of the Queen's University (Canada). Of the surviving buildings, those at Greenwich are mainly in the care of the National Maritime Museum (Royal Museums Greenwich). It was downsized and moved to Cambridge in 1990, and then shut down completely in 1998. In the 1940s and 50s, it moved to the clearer skies of Herstmonceux in Sussex where its name was changed from the Royal Observatory, Greenwich to the Royal Greenwich Observatory, Herstmonceux. It was founded in Greenwich by King Charles II in 1675 for the specific and practical purpose of ‘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 perfecting the art of Navigation’. The Royal Observatory is Britain’s oldest scientific institution. The Royal Observatory Greenwich – A Brief History