How deep are black holes?

What's the biggest thing in the universe? The universe! But it wasn't always so big. It used to be really small ... until the Big Bang changed everything. But who's Steve? Thank you, Scarlett, for the great big question! Theme song, "Space Race," by Tubebackr (https://soundcloud.com/tubebackr).

Black holes are a big deal in our universe, but how big or deep are they? Thank you, Phoebe, for the great (and really difficult to answer well) question! Theme song, "Space Race," by Tubebackr (https://soundcloud.com/tubebackr).

We know the Earth has a moon, but how many other moons are there in our solar system?  Thank you, Nora, for the great question! Theme song, "Space Race," by Tubebackr (https://soundcloud.com/tubebackr).

Our sun is a big star. Really big. But are there stars in the universe bigger than the sun? Thank you, Melody, for the great question! Theme song, "Space Race," by Tubebackr (https://soundcloud.com/tubebackr).