Doomsayers disappointed by 2012′s non-apocalypse will get a sop in 2013 in the form of a rare supercomet. Once widely seen as a portent of doom, comets are seldom as spectacular as the new arrival, known as C/2012 S1 (ISON), may be. At its peak it may outshine the moon, even by day.
First spotted in September, ISON is rushing towards the sun from the outer solar system. Its closest approach to the sun will be in November, when Timothy Spahr of the Minor Planet Center at Harvard University expects it to put on as good a show as Hale-Bopp did in 1997.
This will be its first trip to the inner solar system, so ISON could contain volatile gases that other comets, making their umpteenth lap around the sun, have lost. That will give us a pristine glimpse of the material in the outer solar system 4.6 billion years ago, when ISON formed.
The year will also herald celestial fireworks of a different flavour, thanks to a gas cloud with three times Earth’s mass heading towards the usually placid supermassive black hole at the centre of the galaxy. The collision won’t be visible to the naked eye, but X-ray telescopes will pick up radiation from the shock wave created as the cloud slams into the halo of hot gas around the hole.
As the black hole, called Sagittarius A*, sits a mere 25,000 light years away – on our cosmic doorstep – the crash should provide an unprecedented view of material ploughing into a black hole. It could even yield important clues about what happened 300 years ago, when the black hole was much brighter than now.