This is the clearest, most detailed image of a sunspot ever taken in visible light. These ultra-magnetic structures are thought to be crucial to potentially Earth-threatening space weather, and it's photos like these that will help us better understand the risk.
Sunspots are solar regions that appear much darker than the surrounding area because of extreme magnetic activity. The sudden increase in magnetism blocks convection in the area, which causes a drop in surface temperature. Because they're anywhere from 1,000 to 3,000 degrees cooler than the surrounding parts of the Sun, they become what's known as a black body, which accounts for their apparent darkness. Of course, if you took a sun spot and isolated it from the rest of the Sun, it would still be brighter than pretty much anything on Earth.
Because they're so magnetic, sunspots cause other phenomena such as solar flares, which can disrupt satellites and even expose people in airplanes to radiation. Space weather can, at its most extreme, have even more destructive consequence on Earth, so the more we understand about how these systems form, the better. This particular image gives us our best look yet at a sunspot, and it was taken by the New Solar Telescope at the Big Bear Solar Observatory, which is owned and operated by the New Jersey Institute of Technology.