was he involved in any controversial theory?
Yes. Over the nature of comets and his defense of heliocentrism based on his astronomical observations of 1609
Galileo Galilei
It began as a dispute over the nature of comets, but by the time Galileo had published "The Assayer" ("Il Saggiatore") in 1623, his last salvo in the dispute, it had become a much wider controversy over the very nature of science itself
where is europa located in the solar system It is orbiting Jupiter, and the sixth-closest to the planet of all the 79 known moons of Jupiter when was it discovered? 1610 by whom? Galileo Galilei state any one of its features? It is the smoothest known object in the Solar System, lacking large-scale features such as mountains and craters what is it composed of? Salts such as magnesium sulfate, sulfuric acid hydrate or abiotic organic compounds collectively called tholins who was this above person you mentioned? Astronomer, physicist and engineer can you mention some other notable works of him? Invention of the thermoscope and various military compasses, telescopic confirmation of the phases of Venus, the observation of the four largest satellites of Jupiter, the observation of Saturn's rings, and the analysis of sunspots the first invention that you mentioned just now; what is that? A device that shows changes in temperature when was it invented? 1593 what theories did the above person have on tides? The tides were caused by the sloshing back and forth of water in the seas as a point on the Earth's surface sped up and slowed down because of the Earth's rotation on its axis and revolution around the Sun
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Galileo Galilei [SEP] Controversy over comets and "The Assayer"
In 1619, Galileo became embroiled in a controversy with Father Orazio Grassi, professor of mathematics at the Jesuit Collegio Romano. It began as a dispute over the nature of comets, but by the time Galileo had published "The Assayer" ("Il Saggiatore") in 1623, his last salvo in the dispute, it had become a much wider controversy over the very nature of science itself. The title page of the book describes Galileo as philosopher and "Matematico Primario" of the Grand Duke of Tuscany. Because "The Assayer" contains such a wealth of Galileo's ideas on how science should be practised, it has been referred to as his scientific manifesto.