About 28 million years ago in the distant Whirlpool Galaxy, a blue supergiant star was having a downright miserable time.

The young, enormous star was stuck in a gravitational dance with a greedy partner—perhaps a black hole or a dense neutron star—whose gravity was so intense, it was feeding like a vampire on the star’s exterior. As the star’s plasmas were ripped away, they glowed in x-rays a million times brighter than our sun. 

Then something passed between this far-flung source of x-rays and our solar system, blocking it from our perspective for several hours. Because of how long light takes to travel such incredible distances, x-ray telescopes orbiting Earth didn’t pick up the dip in the signal