Diodorus of Alexandria or Diodorus Alexandrinus was agnomonicist, astronomer[1] and a pupil ofPosidonius.[2][3][4]
He wrote the first discourse on the principles of thesundial, known asAnalemma.[5] a commentary on this having later been written byPappus of Alexandria,[6] that is no longerextant.[7] A small number of sentences having survived the centuries and attributed to him are known; these comment on: the differences between astronomy and natural science, the word meanings for cosmos and star, the nature of stars and theMilky Way. He was known toEudoros. A few surviving passages might come from a commentary onAratus. In his dealings with astronomy he was known toMarinus in his commentary onEuclid'sData containing quotes of Diodorus's opinions on the meaning of a term.[8]