Galileo Galilei
Galileo was an Italian scientist who lived from February 1564 to
January 1642. He was the first born of six children, and he was the
father
of three children. He had two daughters who both joined the convent of
San Matteo, and a son who later married. He is known as the "father of
modern science" for his many achievements. He lived in the time when
the common belief was that the sun orbited the Earth.
Discovering Jupiter's Moons
In 1609, Galileo took the newly invented telescope, which was
basically a child's toy, and turned it into a scientific tool. He had
to adjust the telescope several times because Jupiter is an incredibly
bright planet. In January of 1610 Galileo finally began observation.
The picture
below is a photo of his notes on Jupiter and it's moons.
At first Galileo could only see three of the four major moons of Jupiter, because one was hidden by Jupiter. Over the course of a few days, he saw that there were four moons, and all of them were going around Jupiter, and not orbiting Earth. This proved that everything did not go around the Earth, but that all the planets orbit the Sun. This discovery didn't change everyone's mind however. The church actually made Galileo publically take back what he had discovered and what he thought it meant. There is a rumor that after he had recalled his views, he whispered "Eppur si muove", which means "And yet it moves". In 1757 the church finally approved the idea of the Sun centered solar system, but it wasn't until 1992 that the church formally vindicated Galileo.