broknstrngz tips news of an announcement today from NASA about the discovery of a black hole in the M100 galaxy, roughly 50 million light-years from Earth. The discovery is notable because, if confirmed, it's now the youngest known black hole, born from the remains of a supernova we observed in 1979. Bad Astronomer Phil Plait explains why scientists think it collapsed to a black hole, rather than a neutron star: "The way a neutron star emits X-rays is different than that of a black hole. As a neutron star cools, the X-ray emission will fade. However, a black hole blasts out X-rays as material falls in; that stuff forms a flat disk, called an accretion disk, around the black hole. As this matter falls onto the newly created black hole, it gets heated to unimaginable temperatures — millions of degrees — and blasts out X-rays. In that case, the X-rays emitted would be steady over time. What astronomers have found is that the X-rays from SN1979c have been steady in brightness over observations from 1995 – 2007. This is very strong evidence that the star’s core did indeed collapse into a black hole." He also warns that we're not certain quite yet, and we'll have to keep our eye on it to make sure it's not a pulsar.