Galileo Galilei was an Italian astrologer, physicist and astronomer.
Born on 15 February 1564 in Pisa, Italy, he is best known for his improvements to the telescope, and his own subsequent celestial observations.
He pioneered the use of quantitative experiments, analysing results mathematically – a legacy passed on to him through the influence of his father, a renowned mathematician of his time.
Many of Galileo’s experiments have been reconstructed and authenticated in modern times.
Galileo’s achievements in the field of astronomy include his discovery of Jupiter’s four largest moons – Io, Europa, Callisto and Ganymede.
He was also one of the first Europeans to observe sunspots, and the first to report lunar mountains and craters, deduced from the patterns of light and shadow on the Moon’s surface.
He concluded that the surface of the Moon was rough and uneven, rather than the perfect sphere that Aristotle claimed.
Galileo observed the Milky Way, previously believed to be nebulous, and found it to be a multitude of stars, packed so densely that they appeared to be clouds from Earth.
He also located many other stars too distant to be visible with the naked eye.
On 28 December 1612, Galileo became the first astronomer to observe the planet Neptune. Initially cataloguing it as a fixed star, Galileo considered the 8th planet as unremarkable, and it hardly warranted a mention in his copious notes