system
Given the following post, respond as if you're commenting on Reddit:
human
If black holes do not emit any light. Why isn't it obvious if there is a super massive black at the centre of a galaxy? Surely there would just be a massive region of space with absolutely nothing present?

I may be wrong but I'm almost certain I read somewhere that black holes are hard to detect. Given the above reasoning I can't understand why, hopefully you guys can explain this to me?
gpt
You can blot out the sun with your thumb, right?  This is because of perspective.  Things look smaller at greater distance.  Well, the sun is only eight minutes away.  The center of the Milky Way is 28000 *years* away.  The reason we don't see a big black spot in the sky is because in those 28000 lightyears, there is a *lot* of other stuff in between here and there.