Galileo Galilei example

He was born in the city of Pisa, Italy in the year 1564. He was educated at a Jesuit college in Florence and later did university studies in the branches of mathematics, medicine, and astronomy. He was Professor of Military Engineering and Mathematics at the University of Pisa. His life was largely dedicated to direct observation of various natural phenomena. Among his most outstanding works can be mentioned Dialogue on the two greatest systems of the world, year 1632; and The two new sciences, year 1638.
Galileo placed the telescope in his hands and pointed it towards the sky. The telescope, invented by a Dutchman, was considered in those days a true military secret. They were times of the wars of the Spanish and Dutch. His main function was to foresee the arrival of the enemy sides. Galileo was surprised to see the immensity of stars that existed in the sky. Galileo and his fantastic telescope added impressive evidence that Copernicus's ideas were actually true.
The most important contributions made by Galileo Galilei in relation to astronomical discoveries were: the Via Milky, the existence of mountains on the Moon, sunspots, the phases of Venus and the satellites of the planet Jupiter. He also discovered laws, principles and new methods and instruments of measurement such as the application of the pendulum in the measurement of time, the laws of falling bodies and the statement of the principle of inertia.