The Sun is doing some quite exciting things at the moment. Just the other day, it spat out a X1.7 flare, the first X-class flare this year. Things are likely to stay interesting for a while now too. We’re very nearly at solar maximum – the time when the Sun’s activity is highest.
The Sun, you see, is actually slightly variable. Lots of stars vary their activity over a regular period of time. A main sequence star like the Sun may not vary extravagantly like some others do, but it does have a cycle of about 11 years during which it goes from being fairly quiescent with barely any sunspots, to being quite exuberant with plenty of activity. During solar maximum, a lot of flares and sunspots are likely, which usually means that those who live far to the South and North of Earth can expect to see some dramatic aurorae.
To give you some idea how active the Sun can be near maximum, this image shows one full year of solar activity, courtesy of NASA SDO.
This image is made from a series of 25 images taken from April 16, 2012, to April 15, 2013. These images stacked together show exactly how active the Sun’s been this past year. And it’s really quite beautiful.
This image uses SDO’s 17.1 nm filter, taken in extreme ultraviolet. No really, that’s what it’s called. Extreme ultraviolet (EUV) is high enough in energy that it can show interactions with atomic nuclei and inner electron shells. It’s also high enough in energy, that many fewer photons are emitted by a little yellow star like the Sun at these short wavelengths. All in all, this makes EUV ideal for capturing these gorgeous images, full of plasma trapped in magnetic field lines.
I do find it rather interesting that there are two tracks around the Sun’s surface where sunspots are much more common. They seem to correspond to roughly where the tropics are here on Earth. I don’t know for certain without looking it up, but I suspect it might have something to do with the fact that the Sun doesn’t all rotate at the same speed. It actually rotates faster around it’s equator. Presumably that causes the magnetic field lines either side of the equator to become a lot more jumbled up… But don’t quote me on that. This is all just off the top of my head.