Explained in plain English

What is a polar vortex?

Saturn's newly discovered ten-sided cloud structure is a type of polar vortex. These are persistent, large-scale, low-pressure weather systems that swirl around a planet's poles. On Earth, our polar vortices are usually circular, but on gas giants like Saturn, they can take on surprisingly geometric shapes, like the hexagon at its north pole and now this decagon at its south pole.