 Medieval Islamic astronomers gave Arabic names to many stars that are still used today and they invented numerous astronomical instruments that could <unk> the positions of the stars . They built the first large observatory research institutes , mainly for the purpose of producing <unk> star catalogues . Among these , the Book of Fixed Stars ( <unk> ) was written by the Persian astronomer Abd al @-@ <unk> al @-@ Sufi , who observed a number of stars , star clusters ( including the <unk> <unk> and <unk> 's <unk> ) and galaxies ( including the <unk> Galaxy ) . According to A. <unk> , in the 11th century , the Persian <unk> scholar Abu <unk> <unk> described the Milky Way galaxy as a multitude of fragments having the properties of nebulous stars , and also gave the latitudes of various stars during a lunar eclipse in <unk> . 
