An immense hexagonal storm twice the diameter of earth is locked around the north pole of Saturn.  Humankind discovered the feature by means of the Voyager 1 space probe in 1980 and we continue to study it with our Cassini space probe.  So far, aside from hurricanes on Earth, this is the only eyewall atmospheric feature scientists have found in the solar system (an eyewall is a cloud formation where towering clouds swirl around an empty still center).  Each of the sides of this feature is 8,575 miles long and the eyewall towers 20 to 45 miles tall.  The eyewall clouds do not shift in longitude like the other striations in Saturn’s visible atmosphere.  The huge honeycomb shape rotates every 10 hours 39 minutes and 24 seconds–the same period of rotation as that of the planet’s radio emissions (which is therefore assumed to be equal to the period of rotation of Saturn’s icy interior).  Saturn’s south pole has no comparable feature–although there is a prominent hot spot there.

Nightime movie of the storm taken from the Cassini probe (Image credit: NASA/JPL)