Hubble isn’t dead yet. Not Edwin Hubble, the astronomer from whom it took its name, and who at the beginning of the last century discovered that the universe is expanding (leaving Albert Einstein astonished, because relativity revealed an expanding universe, but since it was believed static had to insert a correction, «the biggest mistake of my life», i.e. not trusting his calculations). Rather the Hubble Space Telescope, which joins the new James Webb Telescope, and which has allowed us to see the first galaxies, thirteen billion light years away.
In short, Hubble has dispelled the fog around an object that has been studied for sixty years, the quasar 3C 273. Quasars almost look like stars but they are not, they are galactic nuclei that emit powerful radio waves, extremely bright due to dust and gas falling into a supermassive black hole (every galaxy has one at the center). But 3C 273, 2.3 billion light years away, fell within an optical band hundreds of times brighter than the previously observed galaxies, so only very powerful light was visible.
Well, here Hubble has allowed a step forward to see the structures around 3C 273, with the use of the Stis coronagraph available in the space telescope. What is a coronagraph? In simple words it is a spectrograph (which analyzes different spectra of light depending on the frequency) used as a coronagraph, that is to block the light of an observed object, and if what has been seen are many small satellite galaxies that are falling into a black hole feeding the quasar, hence its striking glow. Now it’s the James Webb Telescope’s turn to delve deeper.
It’s amazing what next-generation space telescopes are bringing to our knowledge of the universe, and to space objects that have been puzzled over for years.
Suffice it to say that in recent years we have had the first image of a black hole, and we also managed to capture, for the first time, in 2015, thanks to two enormous interferometers, the gravitational waves produced by the collision of two black holes a billion apart and a half light years (so an event that happened a billion and a half years ago, when there were only bacteria on earth). Gravitational waves are the deformation of space-time produced by that catastrophic event, and they were already predicted, as were black holes. Guess who? It goes without saying, from Albert Einstein.