What causes the bright streaks on Dione?
Recent and likely future images of this unusual moon by the
robot Cassini spacecraft now orbiting
might help us find out.
The above image was taken at the end of October from a distance of about one million kilometers.
The bright streaks run across some of Dione's many craters, indicating that the
process that created them occurred later than the
impacts that created those craters.
is made of mostly water ice but its relatively high density
indicates that it contains much rock inside.
Giovanni Cassini discovered Dione in 1684.
The Cassini spacecraft is scheduled to photograph Dione
at higher resolution in mid-December.
highest resolution images of
Dione remain those taken by the passing
Voyager spacecraft in 1980.