A massive gas cloud is on a collision course with the supermassive black hole at the center of the galaxy. As this awesome artist's conception shows, it will be torn completely apart. This is our first chance to watch that happen.
The image up top, courtesy of the European Southern Observatory, shows how the gas cloud will look in 2021, once the supermassive black hole Sagittarius-A* is done with it. Although our own galaxy's biggest black hole is constantly looking to feed, most of the objects in its vicinity have settled into relatively stable orbits, which means they won't be consumed anytime soon. This gas cloud won't be so lucky.
Astronomers have kept watch on Sagittarius-A* since 1992, and in that time only two other objects, both stars, have passed this close to the black hole's massive gravitational whirlpool. Those two stars managed to survive their closest approach unharmed, but as the cloud gets to within 40 billion kilometers of the black hole's event horizon, the gravitational forces will start to rip it apart. Half the cloud will speed up towards the center of the black hole, while the other half will be flung back out into space.
Since it's the only supermassive black hole in our galaxy, Sagittarius-A* is the only one of its kind that is close enough for us to directly observe with any detail. This is our best chance ever to actually see how a black hole consumes giant objects like gas clouds, stars, or planets — but until now, this had all been just theoretical. The action will start within the next two years, and what we learn during that time could revolutionize our understanding of how black holes interact with the larger universe.
Via UC Berkeley. Image courtesy of ESO/MPE/Marc Schartmann.