The chance of it existing somewhere is pretty big. However, our galaxy is huge so the chance of ever encountering them is pretty slim for now Just 500 years ag

The chance of it existing somewhere is pretty big. However, our galaxy is huge so the chance of ever encountering them is pretty slim for now Just 500 years ago, Europeans didn't know about America. It may turn out that aliens bump into us by accident and we find out that they were right around the corner the whole time. Or it is possible that the aliens have the FTL technology to get to us from a point far enough away that our satellites can't see them yet.