ABSTRACT
Johann Kepler, the real founder of modern astronomy, after instruction under Mastlin, one of the first teachers to adopt the opinions of Copernicus, secured the appointment of mathematician at Gratz in Styria, and obtained the notice of Tycho Brahe by dissertations on celestial orbits. The other laws, he verified for all known planets and for the moon, and they have since been proved to hold for all planets and satellites. The first result of these brilliant discoveries was to ensure for Rudolphine tables an accuracy far exceeding that of any previous ones. Contemporary with him and of undying fame in yet another branch of astronomy was Galileo Galilei, more commonly known by his first name. The combination of a convex and a concave lens to magnify distant objects had been accidentally discovered in Holland, and Galileo heard of it. He soon constructed a telescope which magnified 32 times, and turning it towards the moon, discovered the irregularity of its surface.
