Mapping the Sky

Abstract

The first really useful star maps date back to the second century ad. Around the year 150, Ptolemy, last of the great astronomers of Classical times, produced charts which were the basis of others for many years, and which gave us the constellations which we still in use today. All 88 of Ptolemy’s constellations are still there, admittedly with altered outlines. In pre-telescopic times with the maps drawn by the Danish astronomer Tycho Brahe, between 1576 and 1596 were much the best and were amazingly good. Even so, they could not rival maps by telescopic observers and this was why Greenwich observatory was founded, by express order of King Charles II, so that British seamen could use them in navigation. The RGO survived as the headquarters of British astronomy until the end of the twentieth century, when it was wantonly destroyed by the Labour Government. Meanwhile in 1881, David Gill, in South Africa, had realised that the best way to map the stars was to use photographic methods. At the time this was certainly true.