9. They're... Everywhere!
Perhaps the most terrifying thing about black holes is that they're far more common than you'd expect.
In the same way that we, on Earth, are whizzing around the sun, the sun itself is whizzing around an absolutely monstrous black hole at the centre of the Milky Way galaxy, which is a whopping 3.6 million times heavier than the sun.
If this wasn't intimidating enough, some of the bigger stars in our galaxy have a small chance of becoming a black hole if they get too dense on the inside.
The nearest star this has happened to is a mere 1000 lightyears away, which sounds like a very large distance (and it is, given that that's about 6,000,000,000,000,000 miles) but in the grand scale of the universe, it's just down the road.
There could be a black hole even closer than that, but given how hard to see they are, it's a wonder we've spotted as many as we have.