Astronomy Picture of the Day -- Saturn's Iapetus: Painted Moon

NASA ^ | January 13, 2012 | (see photo credit)

[SunkenCiv]

Explanation: What has happened to Saturn's moon Iapetus? Vast sections of this strange world are dark as coal, while others are as bright as ice. The composition of the dark material is unknown, but infrared spectra indicate that it possibly contains some dark form of carbon. Iapetus also has an unusual equatorial ridge that makes it appear like a walnut. To help better understand this seemingly painted moon, NASA directed the robotic Cassini spacecraft orbiting Saturn to swoop within 2,000 kilometers in 2007. Pictured above, from about 75,000 kilometers out, Cassini's trajectory allowed unprecedented imaging of the hemisphere of Iapetus that is always trailing. A huge impact crater seen in the south spans a tremendous 450 kilometers and appears superposed on an older crater of similar size. The dark material is seen increasingly coating the easternmost part of Iapetus, darkening craters and highlands alike. Close inspection indicates that the dark coating typically faces the moon's equator and is less than a meter thick. A leading hypothesis is that the dark material is mostly dirt leftover when relatively warm but dirty ice sublimates. An initial coating of dark material may have been effectively painted on by the accretion of meteor-liberated debris from other moons. This and other images from Cassini's Iapetus flyby are being studied for even greater clues.

[SunkenCiv]

[Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA]

[KoRn]

Wow! That’s a rough looking place!

Looks like that thing has had the hell beaten out of it over time. Some massive craters(to put it mildly) there.

[JRandomFreeper]

What has happened to Saturn's moon Iapetus?

A really, really good block party.

Great pic, btw, thanks. ;)

/johnny

[SunkenCiv]

Looks like Iapetus had the same kind of precip we had the past 30 hours or so.

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[muawiyah]

Burned out Death Star.

[SunkenCiv]

The above pic is from 2007, and is also found here:

http://www.solarviews.com/eng/iapetus.htm

and here:

http://solarsystem.nasa.gov/planets/profile.cfm?Object=Iapetus

[snip] Iapetus has a diameter of 1,471 km (914 miles) and a density only 1.2 times that of liquid water. It has been suggested that Iapetus (like Rhea) is three quarters ice and one quarter rock. [/snip]

[SunkenCiv]

Voyager pics from 1981 show the icy surface as quite shiny, e.g.:

http://www.nasa.gov/mission_pages/cassini/media/cassini-010705.html

http://www.nasa.gov/images/content/105007main_pia06167-330.jpg

and:

http://www.nasa.gov/mission_pages/cassini/multimedia/pia11690.html

http://www.nasa.gov/images/content/411065main_PIA11690-516.jpg

and an animation made from all eight 1981 V pics:

http://www.solarviews.com/cap/sat/viapetus.htm

[SunkenCiv]

A huge impact crater seen in the south spans a tremendous 450 kilometers and appears superposed on an older crater of similar size.

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[PIF]

That's a 12 mile high ridge around the exact equator, further the moon is not round, but hexagonal. No known mechanism in nature can make such a thing.

[Celerity]

This is going to sadden many of you, And I expect that.

Richard Hoagland has some good stuff on this moon. There are a LOT of mysterious, seemingly impossible features on this body. Check out http://www.enterprisemission.com/moon1.htm

I know, I know... Richard Hoagland. I happen to appreciate his style and his findings.

[bmwcyle]

It looks like is was casted.

[SunkenCiv]

Hoaxland’s claims about Iapetus’ artificiality are themselves entirely imaginary, so it’s appropriate that he borrows so heavily from sci-fi writer Art Clarke.

[KoRn]

Looks like it was attacked by the Death Star, and lived.... lol

[SunkenCiv]

:’) If only Voyager had arrived *before* Star Wars...

http://starwars.wikia.com/wiki/Death_Star#Mimas

this too was drolly amusing:

Think Tank: The Economics of Death Star Planet Destruction
http://www.overthinkingit.com/2011/04/25/star-wars-death-star-economics/

[cripplecreek]

KA-POW

[PIF]

Hoaxland’s claims

—

S##ew Hoaxland and what he claims ... There is still the Cassini photos showing the unusual shape and the equatoral ridge. Nothing natural we know of scienticifally about planet/moon formation explains those features.

[Las Vegas Dave]

That's a 12 mile high ridge around the exact equator, further the moon is not round, but hexagonal. No known mechanism in nature can make such a thing.

Hmmmm?

[TheOldLady]

At the time of your post last night, it had been snowing here for 15 hours, and it's still coming down. It's very light though, and not accumulating because of the wind, except in drifts on the driveway in the lee of the house.

That poor moon looks as if it has been thrown a beating or two by the other moons. The Mob is everywhere.

[TheOldLady]

Thanks for all the links, Civ.