Galileo was born in Italy around 500 years ago (in 1564). He was far cleverer than almost everyone he knew and he had a cat’s curiosity for knowledge.

Galileo was a polymath.  That means he knew about many different things.  For example, he knew about maths, physics, philosophy and astronomy (told you he was CLEVER).

Galileo followed his knowledge where it led him (into hot water or not). He is often called ‘the father of modern science’ because he recognised the value of doing experiments as a way to discover how nature works and he used mathematics as a tool to understand nature. He built gadgets to help him to answer scientific questions such as compasses, thermometers, the pendulum and most importantly, telescopes.

Through a telescope, Galileo was able to see the moon and planets in far more detail than anyone could with the naked eye. What he saw through his wonderful telescope inspired him to make his most famous announcement. He announced that in his view, the Earth is not at the centre of the Universe. The news caused quite a stir!

Galileo wasn’t the first astronomer to suggest that the Earth revolves around the Sun. Another astronomer called Copernicus, working in Poland, had already put this forward as a theory. The way Copernicus presented his theory was so complicated that very few people read his book. But Galileo presented the idea in ways that everyone could understand and used his telescopic discoveries to support his view.

Why did this cause such a stir?

The Catholic Church was a powerful force in Galileo’s day and Galileo knew he would need a strong case to support his ideas.

The theory that the Church and most scientists accepted at the time was that the Earth is at the centre of the Universe. It was a view which seemed to fit with the observational evidence and it also seemed to fit with the way that Scripture describes the Universe we live in.

This presented Galileo with two challenges – firstly, did he have the scientific evidence needed to show that the ‘old view’ couldn’t be right, and, also, did he have scientific evidence that his view was true? Secondly, what does the Bible say – if anything – about which should be believed?

Let’s start with the science. Galileo’s reason for rejecting the view that the Earth remains still was this: Through his telescope he noticed that there are moons moving around Jupiter.

Everyone believed that if a planet moved then it would not be able to have a moon. Surely the moon would be left behind, they said.

So, there’s a puzzle – Jupiter is moving (that was plain to see) and according to Galileo, it had moons going around it. This meant, said Galileo, that the Earth CAN move and ALSO have a moon orbiting it. Also, some people thought that there could only be one centre of motion in the universe, but Galileo showed that there were at least two: Jupiter, around which moons moved, and the Earth around which its moon moved.

The officials of the Church were surprised; everyone was surprised! An advisor to the Church suggested getting the observation checked out. Back came the result – yes, Galileo was right. This, however, was not enough to settle the matter. Everyone could see now that Jupiter had moons. Why should they believe that the Earth is also moving through space?

What Galileo needed was firm evidence to show that the Earth is moving around the Sun. It was looking tricky. Galileo did have another clue, and this time it related to Venus. Galileo noticed that Venus seemed to have phases. In other words, Venus seemed to change shape – going from a crescent to a full circle and back to a crescent. That’s what you’d expect to see if a planet is orbiting around the Sun. Was this enough? Now it was obvious that at least one planet, Venus, revolved about the Sun. But this was still not sufficient evidence to show that, in fact, the Earth is moving.

Another reason that his observations were not considered sufficient evidence was that they also fitted with a theory put forward by another astronomer, Tycho Brahe. His theory went like this: the Earth is in the centre of the universe and the Sun revolves around the Earth.  All the other planets go round the Sun – which as you remember, is going around the Earth.

Galileo was a Catholic and believed in God throughout his life

What about the other challenge – the challenge of what the Bible tells us to believe? Galileo thought deeply about how his findings and ideas fitted with Scripture’s descriptions of Heaven and Earth. In his view, it was silly to expect the Bible to tell us how the planets move. He argued that scripture is not about things we can work out for ourselves (like whether the Sun is at the centre of the solar system). It’s about ideas that can only come from God. He said, God has given us senses and brains so that we can study nature and discover how it works. Why would He give us a cheat-sheet in the Bible with all the answers already there?

Galileo decided to go ahead and tell everyone that his theory was right.

The officials of the Church, unsurprisingly, were not happy. Galileo was influential. People respected him – they knew he was clever. Galileo was ordered to keep his ideas to himself.

Galileo agreed and kept silent for a while but before long he was once again talking about and writing about his exciting new ideas. In 1633 Galileo was put on trial for disobeying the Church’s instructions to keep his ideas to himself. He was found guilty and spent the rest of his life under house-arrest, in his home outside Florence. There, he spent his time writing one of the most famous books ever written about science, a book he called The Discourses and Mathematical Demonstrations Relating to Two New Sciences, phew that’s quite a mouthful!

Galileo died at home, eight years after his imprisonment began. In 1992, the head of the Catholic Church, Pope John Paul II said that the Church had made a mistake in condemning Galileo.

The Church today takes the view that there can be no conflict between what science discovers and faith reveals on the basis that God is the author of both reason and faith.