Around 02:00 UTC last night (July 30, 2011), a sunspot named Active Region 1261 erupted with a short solar flare, which was caught by NASA’s Solar Dynamics Observatory. Using Helioviewer I created a short video of the event:

[Make sure to set the resolution to at least 720p!]

Those bright regions are actually sunspots, which are dark at wavelengths our eyes can see, but are quite bright in the ultraviolet. Solar flares occur when the Sun’s magnetic field lines get twisted up. They store a lot of energy, and when tangled they can suddenly snap, releasing that energy. Astronomers classify flares by the energy released in X-rays, from Classes A,B, and C (weak) to M (moderate) to X (yikes!). This one was an M9, which is on the low end of the M class. Powerful, but probably not enough to affect us here 150 million kilometers away. If anything, there may be a stronger than normal aurora in a day or two.

The Sun’s activity waxes and wanes on a roughly 11 year cycle, and we’re on the upswing of Cycle 24. There was an unusually long quiet period after Cycle 23 and ...