“There's a supermassive black hole at the center of every galaxy, and there are also smaller black holes that aren't necessarily in the center.”

“When stars run out of fuel, they start to collapse under gravity, and if they're sufficiently massive, they collapse to an infinitely dense point.”

“There are theories that something is orbiting in the Kuiper belt, which could disrupt objects and send comets and asteroids inward.”

“Mass extinctions on Earth may have been caused by impacts from space, and there are theories suggesting a massive object could be responsible.”