On top of that, galaxies themselves can be terrifying. In a recent The Universe column, I wrote about particularly nasty cosmic nightmares called active galaxies. You see, all big galaxies have a supermassive black hole haunting their heart, and some of these black holes have billions of times the mass of the sun. If matter is falling into one of these black holes at a high rate, that infalling material heats up to frightening temperatures and blasts out high-energy radiation. This also drives intense winds of subatomic particles that flow away at high speed to wreak havoc around the galactic core. That’s all bad enough, but the spin of the black hole can also launch twin beams of matter called jets that can scream across space like death rays, cooking everything in their path for many thousands of light-years.