Title text:
With their 13 years recording and performing together and two humans worth of mass, the White Stripes are sandwiched neatly between gray wolves and blue whales.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3283/
The horizon is what defines the black hole. From the outside the mass distribution is not defined, as there isn’t any experiment you can do that tells you about the internal structure. If you let a mass fall into a black hole you won’t see it cross the horizon, just get asymptotically closer to it.