Black hole makes material wobble around it

The European Space Agency's orbiting X-ray observatory, XMM-Newton, has proved the existence of a "gravitational vortex" around a black hole. The discovery, aided by NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) mission, solves a mystery that has eluded astronomers for more than 30 years, and will allow them to map the behavior of matter very close to black holes. It could also open the door to future investigations of Albert Einstein's general relativity.