No one was supposed to question any teachings about astronomy or physics in the 1500s. Most of the teachings came from ancient Greeks. Galileo thought that the ancient Greeks were wrong about many ideas. He believed that making careful measurements could help people learn accurate facts about astronomy and physics. Galileo was one of the people who began what we now call the modern scientific revolution.

LIFE AND CAREER

Galileo Galilei was born near Pisa, Italy, on February 15, 1564. After attending the university, he taught mathematics. He also observed how things move.

There is a story that he dropped two objects of different weights at the same time from the Leaning Tower of Pisa. He found that light and heavy objects fell at the same rate. The ancient Greek Aristotle taught that heavier objects fell faster.

SCIENTIFIC DISCOVERIES

In the early 1600s, Galileo was the first person to use a telescope to look at objects in the night sky. He discovered many things, including mountains and craters on the Moon and four moons going around Jupiter. Galileo also defended the idea of Polish astronomer Copernicus that Earth goes around the Sun. The ancient astronomer Ptolemy said that Earth was the center of the universe and that the Sun went around Earth. Ptolemy’s system was the official teaching of the Roman Catholic Church. Church authorities ordered Galileo not to defend Copernicus’s theory.

HERESY TRIAL AND CONVICTION

In 1632, Galileo published a book that compared Ptolemy’s and Copernicus’s ideas. The book concluded that Copernicus was right. Galileo was ordered to go to Rome and stand trial for heresy (holding ideas opposed to church teachings). Galileo was forced to say that Copernicus was wrong. Galileo was sentenced to life in prison. He was old and sick, so instead they kept him inside his house. In 1992, Pope John Paul II said the church was wrong to convict Galileo of heresy.

 Source: Microsoft ® Encarta

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