This “ring around the sun” is a halo, an optical phenomenon that occurs from light interacting with ice crystals in the atmosphere. It’s not an uncommon phenomenon, but for those who have never seen one, it’s quite something to behold. Halos can appear around the moon as well as the sun.
At first glance it looks like IceCube winterover Stephan has sprouted some new teeth at the Pole. But they’re just ice clumps, not to worry. Stephan got them while he was participating in a half marathon—and out in the extreme cold, with temperatures around -30 °C, this is not an event for the faint of heart.