Galileo was an Italian astronomer and physicist.

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. With his telescope Galileo claimed to have seen mountains on the Moon, and to have proved that the Earth goes round the sun. This last discovery was considered as heresy and he was condemned to house arrest, for life, at his villa at Arcetri (above Florence).

Whilst working on the laws of motion Galileo dropped different weight balls from the Tower of Pisa to show that they would hit the ground at the same time.