Galileo Galilei was a Tuscan physicist, mathematician, astronomer, and philosopher who played a major role in the scientific revolution. His achievements include improvements to the telescope and consequent astronomical observations, and support for Copernicanism. Galileo has been called the “father of modern observational astronomy,” the “father of modern physics,” the “father of science,” and the “Father of Modern Science.”
His contributions to observational astronomy include the telescopic confirmation of the phases of Venus, the discovery of the four largest satellites of Jupiter, named the Galilean moons in his honor, and the observation and analysis of sunspots. Based only on uncertain descriptions of the telescope, invented in the Netherlands in 1608, Galileo, in that same year, made a telescope with about 3x magnification, and later made others with up to about 32x magnification. With this improved device, he could see magnified, upright images on the Earth – it was what is known as a terrestrial telescope, or spyglass.
Galileo could also use it to observe the sky and for a time he was one of very few who could construct telescopes good enough for that purpose. On August 25, 1609, he demonstrated his first telescope to Venetian lawmakers. His work on the device made for a profitable sideline with merchants who found it useful for their shipping businesses and trading issues.
