The main problem for people in the 1600's:
Galileo Galilei, an incredible space expert, designer, and physicist was conceived on fifteenth February 1564. He was given numerous names like the father of present-day science. Galileo was a keen observer and was able to point out that the Earth and other heavenly objects revolved around the Sun.
But, in that period of time, most of the people were influenced by the Geocentric model that portrayed Earth as the center of the universe and all other objects like the Sun and the stars were moving around it.
As the theory of Galileo was exactly opposite to this, people didn't want to accept it and this became a critical issue for him as he was considered as a religious criminal who was going against god. He even faced trials in the churches and was even sent to jail. The Geocentric model was the biggest problem for the people of the 1600s.