Galileo Galilei was an astronomer who made a number of vital contributions to scientific advancement during his lifetime, but he is most famous for his advocacy of the heliocentric model of the solar system. The Catholic Church forced him to recant his belief and imprisoned him for life.
Galileo's astronomical observations helped confirm and flesh out Copernicus's assertion that the sun rather than the Earth was the center of the solar system. Unfortunately, this conflicted with the official stance of the Catholic Church, which tried Galileo for heresy. He was placed under house arrest for the rest of his life, but he continued to write and study during his imprisonment and continued his contributions to science.