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Jan 7 - Galileo starts a revolution

Updated: May 11


Today in 1610 the Italian Astronomer Galileo made his first observation of the four largest satellites of Jupiter,

which are now named Ganymede, Callisto, Io and Europa. He also was the first to observe and record the phases of Venus, Saturn's rings, and the first to make an analysis of sunspots. Today’s observation of the moons of Jupiter caused a revolution in astronomy as it proved that not everything revolved around the earth. This had huge consequences on how we understood our place in the universe and faced resistance from within the Scientific Community and the powerful Church.... today's pod looks into the story in some detail



Galileo is popularly known as the Italian astronomer who was unjustly punished by the Pope, but the reality is much more complex that this. Born in Pisa, it is probably more accurate to describe Galileo as a polymath, a physicist and an engineer as well as an astronomer. He invented the thermoscope and various military compasses. He was also a committed Roman Catholic, who seriously considered the priesthood as a young man, and two of his daughters became nuns. His fortunes rose and fell as support and opposition ebbed and flowed from inside the church.

He is famous for his observational astronomy include todays first observation of the four largest satellites of Jupiter, which we now know are the moons Ganymede, Callisto, Io and Europa. He also was the first to observe and record the phases of Venus, Saturn's rings, and the first to make an analysis of sunspots. Today’s observation of the moons of Jupiter caused a revolution in astronomy. Up to then natural philosophy had been dominated by Aristotles geocentricism, that everything revolved around the earth. Poof that a planet with smaller objects orbiting it did not conform to the principles of Aristotelian cosmology, which held that all heavenly bodies should circle the Earth. Much of the original opposition to Galileo was from fellow astronomers and philosophers. However when his observations were confirmed by the observatory of the Jesuit priest Christopher Clavius, he received a hero's welcome when he visited Rome in 1611. Galileo continued to observe the satellites over the next eighteen months, and by mid-1611, he had obtained remarkably accurate estimates for their periods—a feat which Johannes Kepler had believed impossible


As his fame grew so did the controversies. For the next decade, Galileo stayed well away from the controversy. But when his friend and admirer Cardinal Maffeo Barberini was elected as Pope Urban VIII in 1623 he was encouraged and forged ahead with writing a book on the subject, the Dialogue Concerning the Two Chief World Systems. This was a bold move, he calculated that the pope would defend him as he had done in an earlier confrontation 8 years before with the Inquisition. The Catholic Church was still traumatised by the Protestant reformation. By revolutionising how we understand the position of the earth, some Dominicans argued that Galileo and his followers were attempting to reinterpret the Bible, where the earth is at the centre of the account of creation in the book of Genesis. The growing consensus around heliocentrism (the sun being at the centre) was seen as a violation of the Council of Trent and looked dangerously like Protestantism.


In a climate which was becoming more heated, when Galileo defended his views he appeared to attack the Pope Urban and thus alienated both the Pope and the Jesuits, who had been his main supporters up until now. He was tried by the Inquisition, and found "vehemently suspect of heresy", and was forced to recant and spent the rest of his life under house arrest. A tragic injustice. The Inquisition's ban on reprinting Galileo's works was lifted in 1718 when permission was granted to publish an edition of his works in Florence. On 31 October 1992, Pope John Paul II acknowledged that the Church had erred in condemning Galileo for asserting that the Earth revolves around the Sun. Saying that the theologians who condemned Galileo did not recognize the formal distinction between the Bible and its interpretation. In 2008