Galileo Galilei (1564-1642) (Jupiter Changer)
Galilei was born in Pisa in 1564, the son of Vincenzo Galilei, well known for his studies of music, and Giulia Ammannati. He studied at Pisa, where he later held the chair in mathematics from 1589 – 1592. He was then appointed to the chair of mathematics at the University of Padua, where he remained until 1610.
During these years he carried out studies and experiments in mechanics, and also built a thermoscope. He devised and constructed a geometrical and military compass, and wrote a handbook which describes how to use this instrument. In 1594 he obtained the patent for a machine to raise water levels. He invented the microscope, and built a telescope with which he made celestial observations, the most spectacular of which was his discovery of the satellites of Jupiter. In 1610 he was nominated the foremost Mathematician of the University of Pisa and given the title of mathematician to the Grand Duke of Tuscany. He studied Saturn and observed the phases of Venus. In 1611 he went to Rome. He became a member of the Accademia dei Lincei and observed the sunspots. In 1612 he began to encounter serious opposition to his theory of the motion of the earth that he taught after Copernicus. In 1614, Father Tommaso Caccini denounced the opinions of Galileo on the motion of the Earth from the pulpit of Santa Maria Novella, judging them to be erroneous. Galileo therefore went to Rome, where he defended himself against charges that had been made against him but, in 1616, he was admonished by Cardinal Bellarmino and told that he could not defend Copernican astronomy because it went against the doctrine of the Church. In 1622 he wrote the Saggiatore (The Assayer) which was approved and published in 1623. In 1630 he returned to Rome to obtain the right to publish his Dialogue on the Two Chief World Systems which was eventually published in Florence in 1632. In October of 1632 he was summoned by the Holy Office to Rome. The tribunal passed a sentence condemning him and compelled Galileo to solemnly abjure his theory. He was sent to exile in Siena and finally, in December of 1633, he was allowed to retire to his villa in Arcetri, the Gioiello. His health condition was steadily declining, – by 1638 he was completely blind, and also by now bereft of the support of his daughter, Sister Maria Celeste, who died in 1634. Galileo died in Arcetri on 8 January 1642.