The Solar Dynamics Observatory never fails to deliver absolutely stunning images from the Sun: as of 18:49 UT today, the above picture is what the Sun looked like in the ultraviolet spectrum. The prominence that you are seeing looping off the Sun is estimated at over 700,000 km across, which is about the radius of the entire Sun. Amazing!
You can head over to the Solar Dynamics Observatory site to watch this gigantic loop of solar plasma develop in real time.
There’s nothing to worry about here on Earth, though – we are safe from such activity on the Sun, even if that prominence is big enough swallow up thousands of Earths. There is no coronal-mass ejection or flare to go along with this prominence, both phenomena on the Sun that can reach Earth and mess with satellites and our power grid.
As you can see (or rather, not see) in this visible light image below, the flare seems to only be visible in the ultraviolet. Other spectra of the Sun as imaged by the SDO are available here. Why is this? Phil Plait, the Bad Astronomer, explains it best:
“In visible light, the light from the extremely thin material in the prominence is totally overwhelmed by the intense emission from the Sun’s surface, and is invisible. It’s only when we filter out most of the Sun’s light (and let through light specifically given off by the plasma in the prominence) that we can see it at all,” he wrote.
This video shows the buildup up this most recent spectacular solar show, as this portion of the Sun comes into view from a 48-hour period between December 4th and 6th:
[UPDATE]: Here is a video that shows the prominence eruption as it expanded:
Spaceweather.com also has some other fantastic images that are linked to on their front page. Prominences like this can come crashing down quickly when they become unstable, so head over to the SDO site to watch the action as it develops!