was there any backlash against his theories?
Yes, against heliocentrism
Galileo Galilei
Galileo defended heliocentrism based on his astronomical observations of 1609. In December 1613, the Grand Duchess Christina of Florence confronted one of Galileo's friends and followers, Benedetto Castelli, with biblical objections to the motion of the Earth. 
what are the four biggest moons of jupiter Io, Europa, Ganymede, and Callisto. who were they first spotted by? Galileo Galilei when was he born? 15 February 1564 which scientific theory is he most well known for propounding? The Starry Messenger
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Galileo Galilei [SEP] Controversy over heliocentrism
However, Tycho countered that since stars appear to have measurable angular size, if the stars were that distant and their apparent size is due to their physical size, they would be far larger than the Sun. In fact, it is not possible to observe the physical size of distant stars without modern telescopes. Galileo defended heliocentrism based on his astronomical observations of 1609. In December 1613, the Grand Duchess Christina of Florence confronted one of Galileo's friends and followers, Benedetto Castelli, with biblical objections to the motion of the Earth. Prompted by this incident, Galileo wrote a letter to Castelli in which he argued that heliocentrism was actually not contrary to biblical texts, and that the Bible was an authority on faith and morals, not science.