How did the equatorial ridge on Saturn's moon Iapetus form?

Apr 01, 2012
Raw image from Cassini space probe of the equatorial ridge on Saturn's moon Iapetus. Image: NASA

Saturn's moon Iapetus is one of the most unusual moons in our solar system.

Perhaps the most bizarre feature of is its equatorial ridge, a 20-km (12.4- mi) high, 200-km (124-mi) wide mountain range that runs exactly along the , circling more than 75 percent of the moon.

No other body in the solar system exhibits such a feature, and as Dombard et al. show, previous models have been unable to adequately explain how the ridge formed.

The authors now propose that the ridge formed from an ancient giant impact that produced a subsatellite around Iapetus.

Tidal interactions with Iapetus ultimately led to orbital decay, eventually bringing the subsatellite close enough that the same forces tore it apart, forming a debris ring around Iapetus.

Material from this ring then rained down on Iapetus, creating the mountain ring along the equator.

Explore further: Image: Comet 67P/Churyumov–Gerasimenko

More information: Delayed formation of the equatorial ridge on Iapetus from a subsatellite created in a giant impact, Journal of Geophysical Research-Planets, doi:10.1029/2011JE004010 , 2012.

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User comments : 11

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kevinrtrs
1.6 / 5 (12) Apr 02, 2012
The authors now propose that the ridge formed from an ancient giant impact that produced a subsatellite around Iapetus.

Whenever there's no naturalistic explanation for any mysterious feature, the magical "giant impact" cause is invoked.

Note how this applies to Mercury's dense core, the formation of the moon, the disappearance of water from Mars, Uranus rolling along in it's orbit, the incredible gouging of Miranda, the supposed extinction cause of Dinosaurs etc. I've probably left out half a dozen or more of such "explanations".

Where is the REAL science behind this kind of explanation? These invocations are ALL unobserved and with zero convincing evidence, bar none.

Spaceman78
3 / 5 (2) Apr 02, 2012
How does the Universe form such magnificent structures following it's own laws. Incredible........and a mystery.
Travis_Grae_Hassig
not rated yet Apr 02, 2012
Obviously an ancient race of advanced aliens...
Teneca
5 / 5 (1) Apr 02, 2012
Incredible........and a mystery
It's apparently recycled research too. The impact theory of Lapetus ridge is researched notoriously (1, 2) and I can't see any progress with it from the above article.
El_Nose
3 / 5 (2) Apr 02, 2012
@kev great examples except the water on mars -- that one is cause Mars has no magnetosphere
Pyle
5 / 5 (3) Apr 02, 2012
Ummm, I usually just ignore kevin but, isn't a celestial impact a "naturalistic explanation"? I believe we observe impacts almost nightly, i.e. "shooting stars". What is magical about rocks running into other rocks?

Oh, and Nose, please don't give even the appearance of encouragement to hit and run theists.
Vendicar_Decarian
5 / 5 (1) Apr 02, 2012
The ridge is formed from a collection of ring material that has been swept up by the moon.

It is patently obvious.
bewertow
2.3 / 5 (3) Apr 03, 2012
The authors now propose that the ridge formed from an ancient giant impact that produced a subsatellite around Iapetus.

Whenever there's no naturalistic explanation for any mysterious feature, the magical "giant impact" cause is invoked.

Note how this applies to Mercury's dense core, the formation of the moon, the disappearance of water from Mars, Uranus rolling along in it's orbit, the incredible gouging of Miranda, the supposed extinction cause of Dinosaurs etc. I've probably left out half a dozen or more of such "explanations".

Where is the REAL science behind this kind of explanation? These invocations are ALL unobserved and with zero convincing evidence, bar none.



...and whenever a natural explanation is provided kevintrs shouts "Hurr durr a zombie wizard who is his own father did it!"
Estevan57
2 / 5 (28) Apr 03, 2012
Space gophers did it. April fools.
El_Nose
5 / 5 (1) Apr 15, 2012
@Pyle

i will respond to whom ever i like, I am a theist. But that does not discredit the fact Mars has no magnetosphere.. and the fact that Kevin made very good points except one.

If you don;t like trolls - then don;t act like one yourself, His argument not mention God, unfortunately i cannot say the same for yours.
Pyle
1 / 5 (1) Apr 16, 2012
Nose:

No, Kevin didn't make very good points. He made a ridiculous statement, that impacts are "magical". He then listed several observations that have been made and appear to be the result of impacts. Impacts are not magical and are in fact common place. Our understanding of physics; observations of the solar system; and our theories of its creation/development strongly suggest that impacts between larger bodies in the solar system occurred.

I don't like to see inflammatory comments stand without pointing out the absurdity of them and, further, exposing the underlying motivation to attack science seemed only fair considering his past behavior. The fact that he didn't mention His Noodly Appendage was the biggest reason I did, to identify him for what he is: a religious troll attacking science. I'd prefer being labelled a troll for my unmotivated attacks instead of when I rise to the call.