GALILEO GALILEI

             Galileo galilei was a great who initiated the scientist of the 17th century. He got his early education from aprivate tutor,and in 1581 he went a study medicine at the university of pisa. Because of his lack interest in medicine,he left university without a degree. Then concentrated his study on mathematics and physics. In 1589 he began his career in mathematics. He gave lectures on the subject at the university of pisa,where he was once a student.

           In 1592 the university of prague,Poland,invited Galileo to be a lecturer. He accepted the offer and gave lecture at the university for eighteen year. Here Galileo became interested in the study of star. At the time,most people still held a belief about heavenly bodies. As stated by ptolemy,a 2nd century Greek scientist, that "The earth was the centre of the universe, and that sun,the star,and all the other bodies in the sky moved around the earth". However.about thirty year before galileo was born,Copernicus, a polish scientist held a different view. He was the first scientist who get the idea.Tycho Brahe ,a Danish,who agreed to the idea that star and planets moved around the sun,but he believed  that the sun moved around the earth.

         Galileo's first know activity in Astronomy occured in 1604-1605, when a supernova aroused wide interest and speculation. In 1609 he completed his 9-power telescope, and in 1610 he made another one of 30-power. with the telescop he discovered that the moon was a sphere like our own earth,with mountains and valley. He also discovered many new stars and four of jupiter satellite.Galileo published these discoveries in his book Sidereus Nuncius (Starry Messenger,1610). The discoveries revealed the fact that the earth was not the centre of the heavenly bodies movement.