[MichaelApproved]

Blackholes I get because I've always considered them big and heard about the massive ones in the center of galaxies but stars felt different because I was used to the size of our Sun.

Not that the Sun isn't big, I just expected other stars to be relatively the same size, give or take a few orders of magnates. These things are so large http://www.kratosguide.com/wp-content/gallery/mind-pictures/...

[RemoteWorker]

Correct me if I'm wrong bu blackholes are compressed matter. They are typically formed by a star that collapses on itself, so they are always very small in comparison. That's why I couldn't believe it when I found out there were some so large. Unless... they become so large by eating worlds over time? Where are all the HN physicists when you need them?

[MichaelApproved]

I believe the singularity point, where all the mass collects, is small (dimensionless) but the gravity well that is created by the mass is what is measured when the size is determined. The edge of the gravity well is referred to as the event horizon. The event horizon of a black hole is the point which matter can no longer escape the gravity of the black hole.

However, I've been wrong several times already in this thread so take it for what that's worth.