Voyager 2 obtained this high-resolution picture
of Saturn's rings on 22 August 1981 when the spacecraft was 4
million km (2.5 million mi) away. Evident here are the numerous
"spoke" features in the B ring; their sharp, narrow
appearance suggests short formation times. Scientists think electromagnetic
forces are responsible in some way for these features, but no
detailed theory has been worked out. Spokes of this nature were
observed to persist at times for two or three rotations of the
ring about the planet. Freshly-formed spokes seemed to revolve
around the planet at the same rate as the rotation of the magnetic
field and the interior of Saturn, independent of their distance
from the center of Saturn. It is therefore suspected that the
tiny dust grains which form the spokes are electrically charged.
Older spokes, which presumably have lost their electrical charge,
revolve with the underlying larger ring particles. (P-23925)
