I was reading this thread,when a thought errupted in my mind:
How big can an asteroid be? What’s the largest mankind has witnessed (via hubble, or other instruments)?
Could a asteroid be as large as our galaxy? If so, what would happen if it came crashing through our galaxy? I’d imagine that the effects of the gravitational pull would effect us long before we actually saw the asteroid, is this true?
If you’re talking about something that’s “as big as a galaxy”, then it wouldn’t be an “asteroid” any more. Dunno what it would be, probably a “rock galaxy”.
As for the biggest asteroid/planetoid found so far, it’s a thing called Quaoar, out in the Kuiper Belt.