Astronomers using new data from the Nuclear Spectroscopic Telescope Array - NuSTAR - and the European Space Agency's XMM-Newton X-ray satellites have measured the supermassive black hole at the center of the spiral galaxy NGC 1365, more than 2 million miles across, and discover it is spinning so fast that its surface is traveling at nearly the speed of light.
A black hole's gravity is so strong that, as the black hole spins, it drags the surrounding space along. The edge of this spinning hole is called the event horizon. Any material crossing the event horizon is pulled into the black hole. Inspiraling matter collects into an accretion disk, where friction heats it and causes it to emit X-rays.