AP Photo

The sunspot responsible for setting off a colorful round of northern lights over the past week got off a doozy of a parting shot today, just as it was about to pass around the edge of the sun's disk.

Sunspot 1402 let loose with an X-class flare, the most powerful class of solar outburst, at 1:37 p.m. ET today, and NASA's Solar Dynamics Observatory captured a sequence of ultraviolet images as the blast went out. Fortunately, this one was not directed right at Earth.