Explanation:
This bizarre, equatorial ridge
extending across and beyond
the dark, leading hemisphere
of Iapetus gives the
two-tonedSaturnian moon
a distinct walnut shape.
With red/blue glasses you can check out a
remarkable stereo composition of this extraordinary feature -- based on
close-up images from this week's Cassini
spacecraft flyby.
In fact, the ridge's combination of equatorial symmetry and scale,
about 20 kilometers wide and reaching up to 20 kilometers above
the surface, is not known to
be duplicated anywhere else in our solar system.
The unique feature was
discovered in Cassini images
from 2004.
It appears to be heavily cratered and therefore ancient,
but the origin of the
equatorial ridge on
Iapetus
remains a mystery.
