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Galileo and His Telescope
You would see mountains, craters, and valleys if you looked at the Moon through a telescope. If you looked at the planet Jupiter, you would see its moons. Galileo was the first person to see these things through a telescope. Galileo was born in Italy in 1564. He lived and worked in Italy all his life.
Galileo did not invent the telescope. It was first made by a Dutch lensmaker. But Galileo improved the design so he was able to study the stars and planets closely. Some people call him the first astronomer. His first telescope magnified what he saw by about three times. Later he built one that magnified by 30 times.
As he studied the sky, Galileo found proof that the planets orbit around the Sun. He was not the first person to believe this, but he was the first to prove that it was true. People of that time believed that Earth was the centre of the universe and everything in space moved around Earth. Galileo got into trouble with the government and the church for saying that what they believed was wrong. He had to take back what he said or else he would have gone to jail.
More Than an Astronomer
Galileo was more than an astronomer. He was an inventor as well. He invented the first thermometer. His thermometer did not measure exact temperatures. But it did show if a temperature was higher or lower or the same as another temperature. He invented a compass that was used for aiming cannonballs shot out of a cannon. Later the compass was used to survey land. He invented a device that used a horse and buckets to raise water. This was used for irrigation.
Galileo thought about the world in a new way. Before Galileo, people did not run experiments or test out their ideas. It was enough just to think about ideas. Galileo wanted to test his ideas and see if they worked in the world. Galileo was one of the first real scientists.
Remembering Galileo
Today we call the four moons of Jupiter that Galileo discovered the Galilean moons. In 1990, NASA sent a spacecraft to Jupiter. They called this spacecraft Galileo.
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