Scientists have know for a while that the core of a sunspot is invariably darker than the area around it. It's also much cooler than the rest of the sun's surface. But why? New research published in Science picks apart the cause, and provides some gorgeous sunspot images in the process.
According to the new study, the dark cores of sunspots are caused by the convection flow of gasses. Using data from the Swedish 1-meter Solar Telescope, researchers gathered enough data to speculate that hot gas rises from the interior of the sun, spreads outwards, cools, and then sinks inward again. If you watch this incredibly trippy eye-of-Sauron-ish video, a time lapse of 53 minutes of sun spot footage, you can see the effect in action. The dark, thin filaments of the core are known as penumbra, and are made up of the lighter columns of gas caused by the convective flow.
Apart from being utterly hypnotic, the video and the information that these scientists have discovered brings us an important step closer to deciphering how sunspots function.