Galileo was a well-known math professor at the University of Padua when he learned about an interesting discovery. In 1608, someone in the Netherlands (most likely Hans Lipperhey, an optician) had invented a device which Lipperhey described (in his patent application)  as “an instrument for looking into the distance.” We know that “instrument” as a telescope - from the Greek words tele [“far”] and scopeo [“I see"].

Fascinated with the device, Galileo  improved  the original design, ultimately magnifying by twenty-one times what could be seen through the glass. Then he did something unusual: He turned his new telescope up - toward the sky. What he saw forever changed  how mankind views the heavens.