NASA says the Sun is "tangled up in blue"

A bright tangle of magnetic field lines has appeared on its surface. But otherwise the Sun is singularly serene. What's going on?
The other day, NASA posted this closeup view of the Sun under the headline: "Tangled Up in Blue."The reference to the Bob Dylan tune aside, I found the video particularly intriguing. That's because the Sun's surface, as imaged here by the Solar Dynamics Observatory spacecraft, is actually quite placid. But there's one exception: a ve