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Galileo's Telescope

2.3 - Galileo's Observations

G. Galilei, Watercolour of the Moon, 1609-1610 (BNCF, Ms. Gal. 48) G. Galilei, Observations of Jupiter's satellites, 1611-1612 (BNCF, Ms. Gal. ??) G. Galilei, Paper Jovilabe, 1611-1612 (BNCF, Ms. Gal. 70)

In March of 1610 the Sidereus nuncius (Starry Messenger) was published in Venice. In this pamphlet Galileo announced to the world the first extraordinary astronomical discoveries made with the telescope: the Milky Way made up of stars, the terrestrial nature of the Moon and the presence of four new heavenly bodies orbiting around the planet Jupiter. This brief text was sensationally successful; the original print-run of 550 copies was rapidly exhausted and the vast echo of Galileo’s discoveries resounded throughout Europe. The following months brought more discoveries, equally important: the presence of spots on the surface of the Sun, the phases of Venus and the three-bodied aspect of the planet Saturn.

These discoveries changed the traditional view of the cosmos and launched a revolutionary process of unification in which the heavenly bodies were to be subjected to the same physical laws that governed the terrestrial ones. All of this shows not only the absolute superiority of Galileo’s telescopes over those of his contemporaries, but also and above all his ability to see the new, there where the advocates of contemporary culture had devised complicated hypotheses in the attempt to salvage the traditional geocentric cosmology.

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