NASA Astronomy Picture of the Day Collection

Iapetus: 3D Equatorial Ridge

This bizarre, equatorial ridge extending across and beyond the dark, leading hemisphere of Iapetus [ http://www.nineplan…] gives the two-toned [ http://antwrp.gsfc.…] Saturnian [ http://en.wikipedia…Saturn's_moons_in_fi ction#Iapetus ] moon a distinct walnut shape. With red/blue [ http://photojournal…VendorList.html#Glas ses ] 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 [ http://hownow.brown…iapetus_flyover_gif/ ]. 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 [ http://saturn.jpl.n…image-details.cfm?im ageID=1270 ] Cassini images from 2004. It appears to be heavily cratered and therefore ancient, but the origin of the equatorial ridge [ http://en.wikipedia…Iapetus_(moon)#The_e quatorial_ridge ] on Iapetus [ http://en.wikipedia…2001:_A_Space_Odysse y_(novel)#Difference s_with_the_film ] remains a mystery.

Cassini Imaging Team [ http://ciclops.org/], SSI [ http://www.spacesci…], JPL [ http://www.jpl.nasa…], ESA [ http://www.esa.int/], NASA [ http://www.nasa.gov…]
Stereo Anaglyph: Patrick Vantuyne [ http://users.pandor…]

Saturn

Goddard Space Flight Center (GSFC)

Jet Propulsion Laboratory (JPL)

Moon

Saturn

Cassini

STEREO

USERS

Iapetus

http://antwrp.gsfc.…

SPD-APOD-ap070915