On Thursday, researchers announced that they’d caught a single, tiny, high-energy particle called a neutrino that had rained down on Earth from a supermassive black hole some 4 billion light-years away.

Astrophysicists are excited because this is only the third identified cosmic object they’ve managed to collect the elusive particles from — first the Sun, then a supernova that went off in a neighboring galaxy in 1987, and now a blazar.

So, what is a blazar, anyway?

A Cosmic Engine