NASA's found the smallest black hole it's ever seen, thanks to the Rossi X-Ray Timing Explorer (RXTE) -- weighing around three times as much our own sun, it's near the bottom weight limit for the super-heavy phenomena. It was discovered by its unique "heartbeat", an X-Ray emission that takes place when gas sucked from a nearby star is swirled around the event horizon until friction causes it to super-heat. The disc then repeats the process every 40 seconds and when examined, looks just like the readout on an ECG machine. After the break we've got a video that talks you through it all and we won't mind if you start booming "Space... the final frontier..." halfway through -- we did too.