17th century illustration entitled 'Six Astronomers' by Joseph Mulder. From left to right: astronomers Galileo Galilei, Johannes Hevelius, Tycho Brahe, Nicolaas Copernicus and Claudius Ptolemy stand around the seated Hipparchus, the classical founder of astronomy. The astronomers are depicted holding binoculars and other astronomical instruments in their hands. In the sky the sun, moon and stars.