Now that November has arrived it's time to get ready for Comet C/2012 S1 (ISON). On November 28 (yes, Thanksgiving Day) at 1:45 pm ET, Comet ISON will fly only 730,000 miles above the surface of the Sun. Even though it is moving as fast as 375 km/s (840,000 mph), the Sun will heat Comet ISON, causing it to sublimate and leave a lot of water and grit behind. Comet ISON is about 2 km across, much bigger than Comet Lovejoy in December 2011, and it will leave a lot of itself behind.
Once the stuff sublimates we will watch for it to light up the corona in the AIA bandpasses. We saw Comet Lovejoy in 7 of the 10 bandpasses in December 2011. This time we will point SDO toward three different places where the comet is predicted to be. One will be centered about the time of perihelion for a half hour on each side of perihelion. The other two will point toward the paths the comet will use to approach and leave the Sun and take data for an hour at each place. The offpoints are much larger than the one we did for Comet Lovejoy in 2011. We expect that the comet debris will look a lot smoother for Comet ISON because the magnetic field that far from the surface is also smoother.
The near-realtime SDO images will be available as self-updating movies at a dedicated website that is being tested and will soon be ready. Until then, there is an ISON campaign website with a lot of good pictures and information about Comet ISON, written by people who study comets. You can also look at the Know Your Night Sky blog for observing hints, especially after perihelion as Comet ISON climbs away from the Sun towards the North Star.
During November we will talk about how much stuff we should see coming off Comet ISON, why the signatures of a sungrazing comet could be like how supernovae work, and how a belt going around two pulleys can help us to understand sungrazing comets.
Make November a month for Sun and comet watching!
