Galileo Galilei

[color=black]Galileo Galilei was one of the
first modern scientists, and made exciting discoveries about stars and planets
using his telescope. He also found out about how things move as they fall to
Earth. He was important because of the way he did his work. He observed
carefully how things behaved and took notes. He then set up experiments to test
his theories.[/color]


[color=black]Galileo knew how to focus
on what really mattered in a problem. And he did not just use words to describe
how things move. He used mathematics. That meant he could say things very
precisely.[/color]


[color=black]Galileo was an important figure
in the Scientific Revolution. This brought a new way of thinking to Europe in
the 16th and 17th centuries.[/color]


[color=orange][b][color=#F79646]GALILEO’S
EARLY LIFE[/color][/b][/color]


[color=black]Galileo was born near Pisa, in
Italy, in 1564. He lived in Italy all his life. His father was a music teacher.
When he was a child, Galileo studied in a monastery. He liked the quiet way of
life there and wanted to become a monk. But his father sent him to the
University of Pisa to study medicine. Galileo did not find medicine interesting
and preferred mathematics. He eventually gave up his medical studies and taught
mathematics instead. Soon, important mathematicians started to take notice of
him. He became a professor of mathematics and taught at the universities of
Pisa and Padua. His work made him famous. The powerful Grand Duke of Tuscany,
Cosimo de’ Medici, made him his court mathematician.[/color]


[color=orange][b][color=#F79646]GALILEO’S
FIRST EXPERIMENTS[/color][/b][/color]


[color=black]In Galileo’s time, people’s
ideas about the world came mainly from the famous Greek philosopher Aristotle.
Aristotle had said that heavy objects fall more quickly than light ones.
Galileo found that Aristotle was wrong. He showed that if you drop a light
object and a heavy object from the same height, they will speed up at the same
rate and reach the ground at the same time. This was a surprise. It went
against Aristotle’s ideas and common sense. But Galileo’s experiments showed
that it was true.[/color]


[color=black]Galileo also looked at
pendulums. He found that they take the same time to complete a swing, however far
they swing.[/color]


[color=orange][b][color=#F79646]WHAT DID
GALILEO DISCOVER?[/color][/b][/color]


[color=black]In 1609, Galileo heard of an
amazing Dutch spyglass that could make faraway things seem close at hand. He
was fascinated. Soon he was making his own telescopes. They were much better
than the early Dutch ones. Then one day he turned his telescope to the night
sky. What he saw astonished him. Galileo found that the Moon had mountains,
valleys and craters. He discovered that Jupiter had four little stars of its
own going round it (he was seeing Jupiter’s four biggest moons). He found that
the pale glow of the Milky Way was in fact the light of many thousands of faint
stars. He watched sunspots. And he saw that the planet Venus showed phases,
appearing as waxing and waning crescents just like the Moon.[/color]


[color=black]These discoveries did not fit in with
people’s ideas about the universe. Aristotle had taught that the heavenly
bodies were smooth and perfect spheres. Yet the Moon clearly was not like that.[/color]


[color=black]Aristotle and the Greek
astronomer Ptolemy had believed the Sun and planets went round the Earth. In
1543 a book by Nicolaus Copernicus, a Polish astronomer, suggested that the
Earth and planets went round the Sun instead. By Galileo’s time, many people
thought it was true that the planets went round the Sun, but they still
believed the Sun went round the Earth. Galileo could see that his work
supported Copernicus. But Copernican theory went against the teaching of the
Catholic Church. The Bible said that the Earth did not move, and was at the
centre of the universe.[/color]


[b][color=orange][color=#F79646]GALILEO
AND THE CHURCH[/color][/color][/b]


[color=black]In Galileo’s day, people could
be tried and even killed as heretics if they wrote books that went against the
Church’s teaching. The Inquisition was responsible for trying heretics. Galileo
hoped he would be safe because the Pope liked his work. So he wrote a book
showing that he believed that Copernican theory was probably true. But the book
was banned and Galileo was tried by the Inquisition. He was forced to say he
had been wrong, and was sentenced to life imprisonment, although he was allowed
to live at home. He carried on working on moving objects, and wrote his most
important book in these last years. Galileo died in Arcetri, near Florence, in
1642.[/color]


[color=black]Galileo’s trial became famous. He had
not wanted to go against the Church. He was a religious man. But he felt that
people should accept what science had shown to be true when they interpreted
the Bible. He thought you should not believe it blindly word for word.[/color]


[color=black]Galileo only had simple
telescopes. And not all of his arguments were correct. But now we have plenty
of evidence that the Earth is just another planet going round the Sun. We have
even found planets orbiting other stars.[/color]


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