Galileo  GALILEI

Born on February 15, 1564, in Pisa, Italy, he was the son of a musician named Vincenzo Galilei. From the get-go, Galileo showed a knack for math and science.

He enrolled at the University of Pisa to study medicine, but his heart was set on the stars. His passion for astronomy led him to drop out of med school and dive headfirst into the world of celestial observation. In 1609, he heard about this new invention called the telescope, and being the curious guy he was, he decided to build his own.

With his homemade telescope, Galileo turned his gaze towards the heavens and made some groundbreaking discoveries. He spotted craters on the moon, observed the phases of Venus, and discovered Jupiter's four largest moons – now known as the Galilean moons (Io, Europa, Ganymede, and Callisto).

Galileo's observations provided strong evidence for the heliocentric model of the solar system proposed by Copernicus, where the Earth and other planets revolve around the Sun. But here's where

'The first thermometer was constructed by Galileo. It consisted of a small glass globe fitted with a long tube. The open end of the tube was inserted in water, and the globe was heated until some of the air was expelled from it. When it was allowed to cool, the pressure of the external air was greater than that of the air in the globe, and so a column of water was forced up the tube, until equilibrium was established. The air thus shut off in the globe formed what we may call the thermometric body, and the top of the water column determined its volume. In using this instrument, as in using any thermometer, it was assumed on the basis of general experience, that when two bodies whose temperature are different are brought into each other's presence, their temperatures will finally become equal. This equalization of temperature is brought about by a lowering of the temperature of the hotter body and a raising of the temperature of the hotter body. It was also assumed that a change in the

'Galileo made his first telescope in 1609, modeled after telescopes produced in other parts of Europe that could magnify objects three times. He created a telescope later that same year that could magnify objects twenty times. With this telescope, he was able to look at the moon, discover the four satellites of Jupiter, observe a supernova, verify the phases of Venus, and discover sunspots. His discoveries proved the Copernican system which states that the earth and other planets revolve around the sun. Prior to the Copernican system, it was held that the universe was geocentric, meaning the sun revolved around the earth.'