At http://phys.org/print308478725.html … astronomers are looking forwards to a collision at the heart of our galaxy. Mind you, it was supposed to have happened last year – but is now moved to a date near you, in three months or so time. The NASA Swift telescope, in orbit, is taking display images of a gas cloud spiralling toward the black hole thought to reside in the centre of the Milky Way. The gas cloud was discovered by astronomers in Germany in 2011 and has been monitored ever since.
Black Holes are actually invisible and the theory is that they don't permit light to escape. It is very hard to find out where they are. However, material falling into them shines in x-rays. It is these x-rays that are imaged by space telescopes – presented to the public as proof of Black Holes.
The get out clause is already being prepared as they aren't sure wha the gas cloud is made from. It is is all gas, it is theorised, the region will glow in the x-ray band for years to come as the black hole swallows the cloud. Another possibility is that the cloud is surrounding the remains of an old star – that is dense. This may mean the results are less spectacular, with the cloud slurped up but the star passing by. It's a bit like waiting for Comet ISON to put on a show. It didn't happen – and it may not happen with the gas cloud. Indeed, if the black hole is shy, or does not exist, nothing at all will happen. What then?