The telescope from Galileo had a magnification of only 30 times. When Galileo looked for the first time with his telescope at the Milky-Way he was astonished about the band of light that stretched across the night sky . Galileo looked at Jupiter and he thought that he saw several new stars near the planet. He discovered four great moons on Jupiter being Io Gallisto Ganymede -and -Europa. They are moving around the planet Jupiter. Galileo determined their orbital periods and he realized that Jupiter and its moons were a mini solar system . Galileo was convinced that his observations were valid and he proved the truth of the copernican model of the Universe. Over the next quarter century Galileo made numerous investigations into the mechanics of motion and weight. Early on he was intrigued by Archimedes investigations into specific gravity and published a work entitled La Balancitta. Galileo's bent was as scientific as mathematical, he suggested methods of testing the behavior of falling bodies using inclined planes. In Padua he gave private instruction in military engineering, mechanics, and astronomy, and made his home into a hostel for his students. Galileo was also creative in devising practical machines: he invented the first accurate clock, an efficient water pump, a precision compass and a thermometer. The Legend is that Galileo tested Aristotle's theories of falling bodies a demonstation that all Europe could hear. He is supposed to have climbed to the top of the Leaning Tower of Pisa and simultaneously dropped two cannon balls, one ten times heavier than the other. Galileo's proofs were all reached by the geometric methods of the Greeks. He valued experiment and personal experience over established authority, and while he was both celebrated and criticized for these views in his own time.The great astronomer Galileo was the first who looked in the telescope and saw the planets and stars for the first time. Galileo Galilei (1564-1642) can be considered as the father of modern physics for astronomy and optics. Galileo was born in Pisa and his father was a musician. Galileo became fascinated with mathematics and geometry through a friend who was teaching astronomy and geometry in Padua. In the summer of 1609, Galileo heard about a spyglass that a Dutchman had shown in Venice. From these reports, and using his own technical skills as a mathematician and as a workman, Galileo made a series of telescopes whose optical performance was much better than that of the Dutch instrument.Hans Lippershey made his first telescope in Holland which was an open tube with glass lenses at each end.