In this edition of Treasures of the RAS, Librarian Jenny Higham introduces the first scientific star atlas, made by Johann Bayer in 1603.
Why do some stars have names with Greek letters in them? Bayer's atlas was the first to identify stars within each constellation by a Greek letter, now known as the 'Bayer designation'.
The atlas includes engravings of the mythical figures of the constellations, but the locations of the stars are based on the best observations of the time. There is also a reference grid on the edges of the maps – making it a forerunner of all later sky atlases.