Galileo Galilei

• 1564: Birth in Pisa, Italy
• 1581: Enrols as medical student at University of Pisa
• 1585: Leaves University of Pisa without degree and works as tutor
• 1586: Invents hydrostatic balance; wrote La Balancitta (The little balance)
• 1589: Appointed to Mathematics Chair, University of Pisa
• 1592: Appointed professor of mathematics at University of Padua, remains 18 years
• 1613: Letter to Benedetto Castelli discussing the rotation of the sun and Galileo's support of the Copernican system.
• 1616 – Officially warned by the Church not to hold or defend the Copernican System
• 1624: Visits Pope who praises and honours him, leaving with assumed permission to publish work on the Copernican vs. Ptolemaic Systems; used a compound microscope
• 1633: sentenced by the Inquisition to imprisonment, commuted to house arrest, for vehement suspicion of heresy in violating the 1616 injunction
• 1642: Death in Arcetri, Italy

He made a telescope with about 3x magnification. He later made improved versions with up to about 30x magnification.[104] With a Galilean telescope, the observer could see magnified, upright images on the earth—it was what is commonly known as a terrestrial telescope or a spyglass. He could also use it to observe the sky; for a time he was one of those who could construct telescopes good enough for that purpose. On 25 August 1609, he demonstrated one of his early telescopes, with a magnification of about 8 or 9, to Venetian lawmakers. His telescopes were also a profitable sideline for Galileo, who sold them to merchants who found them useful both at sea and as items of trade.