A black hole is hard to understand, but this video will really give you some perspective. So how big can they be? Imagine this: crush the Sun to the size of a small town and crush the Earth to the size of a peanut. That's how big they can be.
It's very impressive.
![](https://fooyoh.com/files/attach/images/1098/272/837/014/blachole1.jpg)
Watch the video for more: