Why caused this great white spot on the surface of Saturn's moon Rhea?
The spot was first noticed last year by the
robot Cassini spacecraft now orbiting
Cassini's flyby of Rhea in April imaged in the spot in great detail.
Astronomers hypothesize that the light-colored spot is the
result of a relatively recent
impact on the surface of the icy moon.
The impact that likely created the crater also splashed
light-colored material from the interior onto the darker surface.
Rhea spans 1,500 kilometers across and is the second
largest moon of Saturn after
Rhea sports several other
light colored surface features
that are, as yet, not well understood.