The comet 17P/Holmes that wanders around the solar system every six or so years, suddenly exploded to a size about the size of Luna’s orbit around the earth around October 23-24. You can see it, even in the light polluted cities as its magnitude is about 2.4 and it is the third brightest object in Perseus.
None of the science articles address why the comet when from tightly packed 3.4km to a dispersed 1 million km.
I find this a little disturbing. Who is blowing up our comets? Did it hit something? Did something hit it? Did a pocket of gas inside the thing create enough pressure to turn it from a block of dirty ice to a large cloud of steam overnight? Did an alien surveillance device malfunction and the nuclear generator lose containment?