16 January 2012

Iapetus, a fascinating moon of Saturn - updated

NASA's Cassini spacecraft is returning awesome photos of Saturn, its rings, and its moons, many of them assembled at Boston.com's Big Picture.

I was especially interested to see a closeup of Iapetus, the eighth moon, which has a circumferential ridge around its equator. The photo embedded above is from NASA in 2007. The photo below comes from what I'm sure everyone would consider a "wacko" website that suggests that Iapetus is an artificial (i.e. manufactured) moon.

Certainly the comparison with a Deathstar is striking - and that website is quite interesting (especially if you enjoy pondering conspiracy-theory-type improbabilities).

Whether or not the Iapetus stuff interests you, the rest of the photos from Cassini are truly impressive.

Update December 2010: When I originally posted this is May of 2009, that equatorial ridge around Iapetus was unexplained.  A new hypothesis suggests that this ridge comes not from deformational stresses within the moon, as previously postulated, but rather that it is the remnant of a collapsed ring of debris:
...we propose intact capture or accretion from a debris disk of a "sub-satellite" (possibly more than one) around Iapetus... Such a sub-satellite would be tidally drawn towards Iapetus, once Iapetus is sufficiently despun by tidal interaction with Saturn... Once deep inside the Roche limit, tides would then tear the sub-satellite apart. The resulting debris would collisionally evolve to the equatorial plane, dissipating orbital energy and ultimately raining down on the equator (deorbiting) at subsonic speeds... Assuming the density of ice and a high porosity, rubble-pile structure, all the mass in the ridge can be supplied by a sub-satellite ~100 km in radius, a size relative to Iapetus far smaller than the relative sizes of the Moon to the Earth or Charon to Pluto...
That's from the abstract at the American Geophysical Union meeting.  A BBC summary is here.

Reposted in 2011 to accompany even better photos of Iapetus in an adjacent post.


  1. The title of this post is correct, but your fingers wandered on the keyboard when they typed "Jupiter" in the post itself...

    The Cassini mission has been a true blockbuster for NASA -- a (relatively) inexpensive mission that has not only returned vast amounts of scientific information, but also incredible photographs that have helped the general public remember how awesome space exploration really is. Anyone looking at the still-unexplained central ridge of Iapetus, or the epic ice jets of Enceladus, or the confirmation of liquid ethane on Titan (making it the only body in our solar system, other than Earth, known to have liquid on its surface) can't help but respond with what must be the unofficial motto of the Cassini mission:

    "Whoa. Cool!"

  2. Thank you. That was a rather inexplicable (and immense) typo.


  3. Really? No one?

    Well, alright then...

    That's no moon. It's a space station.

  4. I always assumed that the central ridge is a result of the pressure wave of the huge impact crater.

  5. "Really? No one?

    Well, alright then...

    That's no moon. It's a space station."

    I wish Blogger had a Like button.

  6. If I recall the book correctly, "Japetus" was the site of the Star Gate in Arthur C. Clarke's "2001: A Space Odyssey" - and back then, he predicted a somewhat eye-shaped feature, where the sclera of the eye was a white crater, and the pupil was the Monolith/Star Gate. When higher resolution photos were finally taken, some folks were surprised to find that there was indeed a somewhat eye-shaped crater with a protuberance in the center...

    So, yeah, conspiracy theories about Iapetus have been around for quite a while.

  7. Hi all
    According to the description (9-pages.pdf document) from www.earth-keeper.com the satellite Iapetus the third biggest saturn satellite became the status "space ship" or a "technical construct" based on holy geometry. Belonging to the most Interesting visible aspects is the more than 4 million km large äquatorial wall. Other unnatural forms are dedicated by satellite voyager and cassini sondes.


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