Never forget: the Sun is a star, a mighty ball of ionized gas, and when a star throws a tantrum, even a small one is epic.
And the Sun just sent us a little reminder: NASA's Solar Dynamics Observatory caught this amazing sequence of a sunspot blasting out a flare, then shooting out a long streamer of plasma:
Wow! So what are we seeing here?
SDO views the Sun in many wavelengths, and in this case we're looking at ultraviolet light form the Sun so energetic it's almost X-rays. The bright spot is actually a sunspot! They're dark in the kind of light we see with our eyes* but can be very bright at other wavelengths. Sunspots are regions of intense magnetic field concentration; magnetic loops arc out of the spot, reach into space, then head back down. They seethe with vast amounts of energy, which can be released explosively under some conditions.
That's what happened here. The magnetic field loops in Sunspot 1123 suddenly and cataclysmically released all their energy in the early morning of November 12, blasting it outward as a solar flare -- you can see that as the intense flash of light coming from the bright region in the center of the video. This explosive event also launched a streamer of plasma off the Sun's surface, flowing outward along the Sun's magnetic field. Although the plasma is very hot, we see it silhouetted against the Sun's surface, so it looks dark. This type of streamer is called a filament (had we seen it against the darkness of space, it would look bright, and be called a prominence). You can see it heading roughly in our direction at the end of the video. Don't worry though, it won't hit us!
And as if this weren't enough, along with this event was a small coronal mass ejection. This is when a huge blast of subatomic particles is lofted into space by the Sun, and they sometimes (but not always) occur with flares. Happily for us, the CME will miss the Earth; when they hit they can cause damage to our satellites, as well as mess with our power grid here on the Earth's surface.
However, don't rest easy. We're only at the beginning of this solar cycle, when the Sun's twisted and complex magnetic field is starting to act up. It'll build for the next two or three years, reaching a peak in late 2013 or 2014. We'll probably see some pretty big flares and CMEs then, which means aurorae (yay!) and potential problems with our power grid (boo!). I doubt we'll see the kind of damage breathless doomcriers will no doubt promulgate, but the thing is, we just don't know. Will this be a big, violent peak, or a relatively quiet one?
We just have to wait and see. But I'm glad we have observatories like SDO watching the Sun so carefully. The more we know about it, the better.
Incidentally, I have quite a bit more detail about the Sun, spots, flares, and CMEs in chapter 2 of my book Death from the Skies! Just so's you know.
* I'll note that actually the plasma in the sunspot is very hot, and were it floating in space it would glow very brightly. It only looks dark because the Sun's surface around it is so much brighter.