What they are: Places in space where gravity is so strong that nothing can escape
How they form: When a massive star collapses in on itself
Why they're black: Their gravitational pull is so extreme that even light can't escape
Black holes are places where gravity is so powerful that nothing — not even light — can escape. Rather than being empty, black holes are chock full of matter that gets squeezed into a teensy space. The idea of black holes was first proposed in 1916, but at the time, physicists didn't think they actually existed. Today, we know that black holes are all around the universe, from far-away galaxies to the center of our own Milky Way. Read on to discover everything you need to know about how black holes form, what it's like inside of a black hole and what would happen if you fell in one.
