Galileo challenged the Church's view that the Earth was the center of the universe by claiming that the sun was central. This led to Galileo being charged with heresy and placed under house arrest. During the Renaissance, attitudes toward science changed as people began to question established beliefs and use observation and evidence to draw conclusions. Martin Luther criticized the Catholic Church's sale of indulgences, sparking the Protestant Reformation and a split from the Catholic Church. The printing press allowed knowledge and new ideas to spread more widely.