Copernicus was considered a heretic and wrong, but he knew what he knew

Wonder what his distractors would have to say now, when even the sun is just a dustmote in the Universe. Hold it, there are still people who believe that Earth is the center of the Universe.

I've always heard that "Ignorance is bliss", but we know that's not true. However, I've never figured out how one knows when one is ignorant of something important. You don't know what you don't know -- and that's a fact!

Lol, I know what I know, but I don't know what I don't know.