Galileo was the eldest of six children. He went to school in a monastery and thought about becoming a monk himself.

But his father wanted him to become a doctor. Galileo started studying medicine. But then he changed to maths.

Galileo was very talented. He could have been a musician or an artist. But maths excited him most. At just 25, he became chair of maths at Pisa.

By the time he was 28, Galileo was teaching geometry, mechanics and astronomy at the University of Padua. These were dangerous subjects to be teaching at the time. The Roman Catholic Church was extremely powerful. According to the Church, the earth was the centre of the universe.

But Galileo would later develop the strongest telescope the world had seen. He would realise the Church was wrong.

Galileo made many breakthroughs in physics. But it was his observations of the heavens that changed the world. After many years of gazing at the night sky with his telescope, he published a book about what he had seen. For example, he saw moons circling Jupiter. This helped him reach the conclusion that the earth circled the sun.

Galileo was put on trial. He was accused of heresy - disagreeing with the ideas held by the Church. He spent the rest of his life under house arrest. The Roman Catholic Church did not forgive him until 2000.

The year of astronomy

Fill in the blanks: powerful, Jupiter, galaxy, telescope Last year was the International Year of Astronomy. This is because 400 years previously, in 1609, Galileo first turned his ___________________ on the night sky.

One of Galileo's first discoveries was that there were mountains on the moon. He also saw moons circling ___________________, and constellations of stars.

To celebrate Galileo's amazing achievement, some of the most ___________________ telescopes in the world, including the Hubble Space Telescope, collaborated to create an image of the heart of our ___________________, the Milky Way.

A moving earth

Find words that mean the opposite: Wholly, old-fashioned, end, towards

Galileo was not the first person to suggest the Earth went around the sun. Ancient Greek philosophers considered the same idea. Ancient Indian scholars may have done, too. But the Polish Nicolaus Copernicus (1473-1543) was the first modern thinker to explain why he thought this was so.

In the year Copernicus died, he published On the Revolutions of the Celestial Spheres. Many scientists now think this book was the beginning of modern science. Copernicus explained that it was not necessarily true that other bodies in the sky revolved around the Earth.

The Church took no action against Copernicus. Perhaps because what he wrote was just a theory. But Galileo proved his theory with a telescope.

Copernicus' theory was partly right. It is called a heliocentric theory of the universe. Like Galileo, he thought that the sun was the centre of the universe. We now the sun is just one of billions of stars in our galaxy.

True or false?

To test your memory, try answering without referring to the text. If you can't remember the details, read the piece again.

1 Galileo's father wanted him to become a lawyer.

2 Galileo discovered moons circling Jupiter.

3 Galileo thought the sun was the centre of the universe.

4 Galileo died under house arrest for going against the Catholic Church.