In the past year we have figured out one way the comet tail can be bright in the solar corona. (Check out the paper at the Physics ArXiv site.) But we still don't know how the solar magnetic field affects (and is affected by) the comet as it moves through. All of that stuff coming off the comet makes the field shake, can we learn something from that? The brightness of the comet debris comes from running into electrons in the corona. Can we learn about the number of electrons in the corona?
We need even bigger sun-grazing comets!
Since Comet Lovejoy we have had only one alert to look for a comet in SDO and we saw nothing. But Comet ISON is due on Thanksgiving Day next year. It was acquired out near Jupiter, which usually means it is a big comet. As it moves toward the Sun, people are watching to see if stays bright. If it does we will be in for quite a show. Comet Lovejoy came in from the south and was seen only in the southern hemisphere. Comet ISON is coming in from the north and could be visible from the United States both inbound and outbound. Comet ISON will also pass through the corona a little farther out than did Comet Lovejoy, 1.2 million km (1.9 million miles) above the Sun's surface.
It would be like fireworks on Thanksgiving!