Bayer, Johann. Hydra, 1603

Johann Bayer Hydra From "Uranometria, omnium asterismorum continens schemata..." Augsburg, 1603 approx.: 13 1/2" x 17" Bayer was the first accurate star atlas.  A lawyer and amateur astronomer, he was the first to signify the location of the stars within a given constellation by the use of Greek letters (with the addition of the Latin alphabet for constellations with more than 24 stars). This strikingly simple innovation greatly improved the identification of stars with the naked eye, just five or six years before the invention of the telescope. Bayer's stellar nomenclature is still in use today.