A polar vortex is (in the words of Wikipedia) “a persistent, large-scale cyclone located near the Earth’s poles.” But some other planets have them too. Saturn, for example, has vortices at both of its poles. The south polar vortex is pretty typical; it looks like a giant hurricane. But Saturn’s north polar vortex is hexagonal. Nobody knows why.
When I saw the pictures of Saturn’s polar hexagon, the first thing I thought of was the Well of Souls series of novels by Jack Chalker. It takes place on the Well World, a planet almost entirely tiled with hexagonal features that are visible from space. But the Well World is an artificial structure. And, ironically, the poles are among the few parts of it that are not covered by hexagons. (The only other exception is the equator.)
So Saturn’s polar hexagon must be caused by something else. I’ll bet there’s a black monolith at the center of it.