Who is considered as the father of modern astronomy?
Googling is giving me both Galileo Galilei and Nicolas Copernicus as the answer. I am sorry and will remove this question if it is an opinion based question.
It is opinion based, I'm afraid. What constitutes "modern astronomy" and who is the "father" of it are not things that can be decided in any other way.
I like the Hubble answer. I'd define modern astronomy as the discovery that the Universe extended beyond the Milky way. Einstein was obviously huge. I might call him the father of modern science. (Opinion based, obviously). Fritz Zwicky isn't a bad answer for the father of modern astronomy either.