The spokes of what structures that distinguish saturn appear seasonally, with an origin as yet unknown?
satellites
moons
craters
rings
An animation of dark spokes in Saturn’s rings is seen here: http://en. wikipedia. org/wiki/File:Saturn_ring_spokes_PIA11144_300px_secs15.5to23_20080926. ogv . The spokes appear seasonally and their origin is as yet unknown.