Holy cow, thanks to Emily Lakdwalla and mars_stu, here is a freaking enormous loop of plasma arcing off the surface of the Sun:
[Click to enfilamenate.] That was taken by the Solar Dynamics Observatory at about 17:50 UT, or just an hour or so ago as I post this. Wow! That prominence must be nearly a million kilometers across!
[Update: Geeked on Goddard estimates it at 700,000 km.]
Mind you, on the scale of this image, the entire Earth would be about 5 pixels in size. Yegads. OK, a few things: 1) First, there is very little danger to Earth from this event. Prominences like this tend to be local to the Sun, and collapse after a few hours. As far as I can tell, there are no flares or coronal mass ejections associated with this, which are what can hurt satellites and power grids here at home. So rest ...
