Telescope Invention
In May 1609, Galileo received a letter from Paris French Badovere Jacques, one of his former students, who confirmed a persistent rumor: the existence of a telescope to view distant objects. Made in Holland, would have allowed the telescope to see stars and invisible to the naked eye. With this single description, Galileo, no longer gives courses to Cosimo II de 'Medici , built his first telescope. Unlike the Dutch telescope, it does not distort the objects and increases 6 times, or twice as his opponent. It is also the only of the time getting right to obtain an image through the use of a diverging lens in the eyepiece. This invention marks a turn in the life of Galileo.
August 21, just finished his second telescope (increases eight or nine times), is presented to the Senate of Venice. The show takes place at the top of the Campanile the Piazza San Marco . The spectators are excited, their eyes, Murano, located 2 km and a half, seems to be 300 m only.
Galileo offers his instrument and the rights bequeathed to the Republic of Venice, very interested in military applications of the object. As a reward for life is confirmed in his post in Padua and its emoluments are doubled. Released by end of financial hardship.
However, contrary to its claims, did not dominate the optical theory and the instruments made by him are of very variable quality. Some telescopes are virtually unusable (at least in astronomical observations). In April 1610, in Bologna, for example, demonstration the telescope is disastrous, as well as Martin Horky reported in a letter to Kepler.
Galileo acknowledged in March 1610 that, among more than 60 telescopes were built, only a few were suitable. Numerous witnesses, including the Kepler confirm the mediocrity of the first instruments.
The Moon Observer
During the fall, Galileo continued to develop his telescope. In November, made an instrument to increase twentyfold. Uses time to turn his telescope toward the sky. Quickly looking at the phases of the moon, he discovers that this star is not perfect as I wanted Aristotelian theory. Aristotelian physics, which had authority at that time, distinguished between two worlds:
- the world "sublunary" , including the Earth and everything that lies between Earth and Moon, in this world everything is imperfect and changing;
- the world "supralunar" , which begins on the Moon and extends beyond. In this area, there are only perfect geometrical shapes (spheres) and immutable regular movements (circular).
Galileo, meanwhile, was a transitional area between the shadow and light, the terminator , Who was not at all regular, which therefore invalidated the Aristotelian theory asserts the existence of mountains on the moon. Galileo even estimated its height at 7000 meters above the highest known mountain in the period. It must be said that the technical means of the time not possible to ascertain the altitude of the mountains without fantasy land. When Galileo published his Sidereus Nuncius think the lunar mountains are higher than those on Earth, but in fact are equivalent.
head thinking about the stars
Within weeks, you will discover the nature of Galaxy , count the stars in the constellation of Orion and notes that certain stars visible to the naked eye are indeed star clusters. Galileo observed Saturn's rings but does not reveal its nature. Also studied sunspots.
The January 7, 1610, Galileo made a capital discovery: highlights three small stars on the periphery of Jupiter. After several nights of observation, discover which are four, rotating around the planet. These are the satellites of Jupiter Galilean satellites called today : Calixto, Europe, Ganymede and Io . To protect the need and no doubt eager to return to Florence, Galileo will call these satellites for some time the 'stars mediciens "I, II, III and IV, [ 14 ] in honor of Cosimo II de 'Medici, his former student and Grand Duke of Tuscany . Galileo has not hesitated between Cosmic Medicea considers and considers . The pun between cosmic and Cosme is clearly voluntary and is only after the first impression holds the second name (the actual name of these satellites it should however the astronomer Simon Marius, who named this way as suggested by Johannes Kepler, but for two centuries, Galileo used the nomenclature).
The March 4, 1610, Galileo published his discoveries in Florence in The messenger of the stars ( Sidereus Nuncius ), a result of his first stellar observations.
For him, Jupiter and its satellites are a model of the Solar System. Thanks to them, believes he can prove that the orbits of Aristotle crystal do not exist and that all heavenly bodies do not revolve around the Earth. It's a hit very hard to Aristotle. He also corrects some Copernican who claim that all heavenly bodies orbit the Sun
April 10, shows these stars to the court of Tuscany. It is a triumph. The same month, provides three courses on the subject in Padua. Always in April, Johannes Kepler offers support to Galileo. German astronomer not really confirm this finding - but enthusiastic - until September, thanks to a lens offered by Galileo himself.
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