Two natural-colour images from NASA’s Cassini spacecraft show the region inside Saturn’s north polar hexagon changing from bluish in November 2012 to a more golden hue in September 2016. The change is thought to be seasonal: as the north pole approached its summer solstice in May 2017, sunlight drove the production of more photochemical haze in the atmosphere.
During the long polar winter night, from November 1995 to August 2009, the north polar atmosphere cleared of these aerosols. Since the August 2009 equinox the pole has been in continuous sunshine, and haze has been building up inside the hexagon. The hexagon is a six-sided jet stream that may act as a barrier, keeping out haze particles produced outside it. Changes in atmospheric circulation and seasonal solar heating of the polar winds could also play a part.
via Changing Colors in Saturn’s North | NASA