"The great man [Galileo in 1610 on 24 and 25 April] was asked to demonstrate the Jupiter moons in the spyglass. Not one among the eminent guests was convinced of their existence. The crude nature of the mysterious gadget did not help. But many were blinded by bias — they refused to look down the tube...Kepler was the only weighty voice raised in defense...The revolution in science begins with the discovery of these ‘alien’ worlds and the names of Galileo and Kepler have come to symbolize that revolution."