Galileo's Telescopes And Discoveries

We have seen in Galileo Lays The Foundations For Greatness that he had begun a brilliant career with early success and recognition.

By the time he was 28 years old, he was at Padua University, holding his second Professorship of Mathematics. He had unfortunately needed to leave the university of Pisa and his Tuscan homeland, having already upset the authorities there.

Here in Padua, he was to start the work that was soon to revolutionise science.

Galileo so loved inventing equipment to help his work, that he had a skilled instrument maker live with him at his house.

So when he found out about the very first telescopes being made in Flanders, he started to make his own telescopes and improved them.

He was also clever enough to demonstrate his telescopes for important people. He gave away many as gifts, to those people with influence around Venice.

Galileo used his new telescope himself, of course.

With it, he was able to see many thing that were obviously inconsistent with the classic Aristotle view of the perfect universe, with everything revolving around the Earth.

He saw that the Moon was cratered and the Sun had spots on it – both less tha “perfect”.

He saw that the Milky Way was composed of countless stars, made visible simply by using the telescope. These must be further away and not stuck to the same “crystal sphere”, at the same distance from Earth, as the stars that could be seen unaided.

Then there was the most significant discovery – he saw four moons clearly orbiting aound Jupiter.

These astonishing views he saw through his telescope, made it clear to Galileo that the heliocentric (Sun-centred) model proposed by Copernicus some sixty years earlier – the model that had received such vehement opposition from the Church and authorities – was likely to be the true one.

Interestingly, Galileo’s telescope was not good enough to see the rings of Saturn with any clarity. He recorded that Saturn had a blob on each side…

But if any evidence is needed that his observations were meticulous, then his discovery of the libration of the Moon surely provides it. We are familiar with the fact that the same side of the Moon is always faces the Earth. The libration phenomenon is a slight variation in rotation that lets us see sometimes slightly more to the east, west, north or south of the surface than usual. You have to observe very carefully to notice this.

Galileo first got into trouble with the Holy Roman Church, shortly after the Church condemend Copernicus’ book as heresy in 1616.

It was suspected (with good reason,) that Galileo was promoting the Copernican ideas that the Earth went around the Sun. Galileo, himself a devout Catholic, was forbidden to teach or promote any of this heresy.

Some years passed and he had favourable contact with two successive Popes and felt that attitudes were changing.

He went ahead and wrote his most important work, “The Dialogue Of The Two Systems”. This examined the evidence in favour of both the Earth-centred system and the Sun-centred system.

He sent it to the Church for review and after many years delay, received permission to publish in 1632.

Unfortunately, Galileo’s problems really begun at this point.

In October 1632, he was summoned to the Inquisition in Rome, charged with heresy. This was rather serious! He attended in 1633.

When he arrived, it could of been made a lot worse for Galileo. His powerful friends helped him. He was allowed to stay at the house of the Tuscan ambassador, rather than in prison.

But his book, the Dialogue, was condemned. He had treated the question of the Earth and its motion, as a subject for discussion, when it was not. He had also slanted the arguments in favour of the Sun-centred model, which was at odds with Church doctrine.

He was therefore strongly suspected of heresy.

He had to be punished.

Galileo was forced to swear he would never speak or write again, about the Copernican model which said the Earth orbited around the Sun.

He was also imprisoned, although this was interpreted leniently as solitary house arrest.