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In the winter of 1609 and 1610, Galileo Galilei turned a telescope he had built himself to the night sky and saw what no one had seen before: mountains and…
In the winter of 1609 and 1610, Galileo Galilei turned a telescope he had built himself to the night sky and saw what no one had seen before: mountains and valleys on the Moon, which was not a perfect sphere; countless stars invisible to the naked eye, which make up the Milky Way; and four 'stars' near Jupiter that moved night after night, which he realised were moons circling the planet. This short book, published in March 1610, announces those discoveries.
Context and significance
Galileo (1564–1642) named Jupiter's moons the 'Medicean stars' after the Medici, who soon became his patrons. The discovery that bodies could circle something other than the Earth was strong evidence for the Sun-centred system of Copernicus, and set Galileo on the road to his trial by the Inquisition. This is the 1880 translation by Edward Stafford Carlos. Compare Einstein's Relativity.
About the author
Galileo Galilei (1564–1642) was born in Pisa and taught mathematics there and at Padua. He studied falling bodies and pendulums, and in 1609 built a telescope with which he discovered the moons of Jupiter, the phases of Venus and the mountains of the Moon, which he announced in The Sidereal Messenger.
His defence of the idea that the Earth moves around the Sun brought him before the Inquisition in 1633; forced to recant, he spent his last years under house arrest near Florence, where, going blind, he completed his book on motion that prepared the way for Newton.