Yesterday, an active region on the sun – basically, a collection of magnetically active sunspots – popped off a series of flares that were actually fairly energetic. NASA’s Solar Dynamics Observatory caught the action in this video:
Neat! These shots were in the ultraviolet, where flares are easier to spot.
Sunspots are where the Sun’s complex magnetic field pokes through the surface. The field lines store ridiculous amounts of energy (did you see my BAFact for today?), and allow plasma – superheated, ionized gas – to flow along them. Think of these field lines like a pillowcase full of tightly wound springs. If one of them snaps – which can happen if they get too close to each other, for example, or when the churning surface of the Sun ratchets up the tension in the field lines beyond their capacity to restrain themselves – it blasts out its energy, which then snaps other lines, which release their energy, and so on. You get a cascade of explosions, resulting in a solar flare.
Flares can be pretty small, or hugely huge. Scientists categorize them by the amount of X-ray energy released, so we have low-energy C class, medium M class, and yikesingly X class. This flare from yesterday just edged into X class territory, so it was decent, but not too bad. Happily it was on the edge of the Sun, and the blast was directed away from Earth, so it’s not expected to affect us. For further reassurance, there have been 14 previous flares since this new sunspot cycle began a couple of years ago, and we’re still here.
However, as the Sun spins, this active region is rotating toward us. If it stays active, we could see some interesting events from it that can cause aurorae on Earth. The odds of anything bad happening – power outages, or loss of satellites, for example – are low, but not entirely zero. I personally am not too worried about it, but it’s always good to keep our eyes on our nearest star. It can pack quite a punch, and we’re still a year or so away from the peak of the current sunspot cycle.
Image credit: NASA/SDO
Active Region 1402, the same sunspot cluster that blew out a solar flare and caused all the ruckus last week, is still being feisty: just before rotating to the other side of the Sun, it erupted in an intense, pulsing solar flare that actually was much more powerful than the one that happened last Monday. This was an X2 class flare, making it more than twice as energetic as Monday’s.
Happily, the flares were on the edge of the Sun’s disk, so the bulk of the radiation was aimed away from the Earth, but it still makes for some pretty dramatic footage. Using helioviewer.org I created a video showing about 2.3 hours of the Sun as seen by NASA’s Solar Dynamics Observatory. It shows the Sun in the extreme ultraviolet (at a wavelength of 19.3 nanometers if you wanna get geeky), where magnetic activity is seen easily. Watch the upper right corner of our friendly star… and make sure you make it HD and full screen.
Isn’t that awesome? The flare got so bright the automatic software dimmed the rest of the Sun to compensate, giving you an idea of just how powerful these flares can be: at peak, they can give off several percent of the entire Sun’s brightness in one small spot! I love how you can see it pulsing over the course of several minutes; I counted 10 separate flaring events. Each pulse was from a snapping of the Sun’s magnetic field lines, a cascading series created when the first one went off and triggered the rest. And each released mind-numbing amounts of energy — tens of thousands of times our entire planet’s nuclear arsenal combined. Also, you can see the arcing loop around the flare site; that’s plasma trapped in a field line. It erupts outward, but bear in mind the scale: it’s several hundred thousand kilometers across, roughly the distance from the Earth to the Moon, and it blasts away from the Sun like the devil himself is after it.
Like I said: awesome.
You might have noticed the flare looked like an elongated diamond. That’s not real! It’s a digital artifact; what’s happening is the flare got so bright it overwhelmed the pixels in the SDO detector. These collect light like a bucket collects rain. If too much light hits them, they overflow into the neighboring pixel. This flare was so bright it flooded the detector, and created that effect — technically called blooming.
We haven’t seen much of an effect from this flare — just a minor radiation storm that’s at the lowest end of the scale, nothing to worry about — since it wasn’t pointed at us. Had this been in the center of the Sun’s disk, well. That might’ve given me my chance to finally see some aurorae from Colorado. Not this time, though, and sunspots generally don’t last long enough to make it all the way around the Sun again (which takes about 30 days to spin once). But the Sun has a lot of magnetic energy still up its sleeve, and we’ll be seeing more flares like this as we approach the peak of the cycle in 2013 and 2014.