At https://phys.org/news/2021-11-largest-comet-near-record-distance.html … the largest comet ever observed seems to have been active a long way out from the Sun. Largest ever is restricted to modern observations, of course, and doesn't mean that historically, there may have been comets as large, or larger, visiting the inner solar system. Comet Bernardelli-Bernstein [hereafter Comet BB] is estimated to be one thousand times bigger than the average run of the mill comet. The largest one seen in modern times – which could perhaps be confined to modern big telescopes rather than the hand held variety in use over hundreds of years. It has had a coma from a long way out. This means the comet is already vapourising we are told – or perhaps it is being titillated by the solar wind at the far reaches of the solar system. The article goes on to quote the mainstream mantra that comets are dirty snowballs or ice dirtballs, in spite of several encounters by space vehicles with comets which may suggest otherwise. They are conglomerations. Are they conglomerations of rock that fall apart easily as a result of more intense bouts of solar wind [plasma] as comets around the Sun or are they conglomerates of dust and ice, as mainstream prefer?
They think Comet BB was probably active long before it was picked up by observation by astronomers, and it is likely, they say, that carbon monoxide is involved in the sublimation process as this is capable of dissipating before other chemicals in comets. Have they over estimated the size of the comet by its activity? We shall have to wait and see as it comes closer – which will be some time.
At https://phys.org/news/2021-12-astronomers-strangely-massive-black-hole.html … concerns a huge black hole in the heart of one of the dwarf galaxies which are satellites of our Milky Way galaxy. It was an unexpected result as it seems to be as powerful as the black hole at the heart of the much bigger Milky Way galaxy. This is odd, because of the size differential. Of course, they can't actually see black holes. Is there a clue somewhere in that fact? For example, they measured gravitational pull to estimate how much dark matter was in the dwarf galaxy. It was a supercomputer that screamed back at them, in their words. You need a black hole at the centre to compensate for the little dark matter they estimated from the previous calculation. The researchers noted, the result was different to past studies of the dwarf galaxy due to a combination of better data and supercomputer simulations. Now, I just wonder …
We are back to comets in item 3 – at https://phys.org/news/2021-11-comet-a1-leonard-brightens-december.html … Comet BB won't be around for quite a while but we do have Comet A1 Leonard in the more immediate future – and it is brightening. It will possibly be a naked eye comet – see also https://spaceweather.com December 2nd. It is named after an astronomer at an observatory in Arizona who spotted it back in January. It will pass the perihelion in early January when it will be 0.62 AU from the Sun, interior to the orbit of Venus. Predictions are that it will reach + 4th magnitude, on the edge of naked eye visibility. It will pass closest to earth on December 12th, next week. The Sun-Earth-Comet phase angle for the tail will sit at greater than 120 degrees from December 9th to the 22nd and reach a maximum on December 14th. This sets up conditions for a surge in brightness – although this is not certain. Expectations, however, are high. The planet Venus actually passes through the tail of the comet on December 19th. One to watch. It may create a meteor swarm that will plunge into lower atmosphere of Venus. Best to view the comet at dawn until mid December, when it switches to dusk.