CICLOPS: Cassini Imaging Central Laboratory for OPerationS

Chiseled Away
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Giant craters like the one seen in this view deform the shape of Hyperion, making it the largest irregularly shaped body in the Saturn system.

The moon has such a low density--about half that of water--and such low gravity that impactors tend to compress its surface, rather than excavating it, and most material that is blown outward never comes back.

Hyperion is 270 kilometers (168 miles) across.

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 23, 2007. The view was obtained at a distance of approximately 318,000 kilometers (198,000 miles) from Hyperion. Image scale is 2 kilometers (1 mile) per pixel.

[Caption updated February 12, 2008]

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission, visit and the Cassini imaging team home page,

Credit: NASA/JPL/Space Science Institute
Released: September 14, 2007 (PIA 09728)
Image/Caption Information
  Chiseled Away
PIA 09728

Avg Rating: 8.28/10

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Alliance Member Comments
Mercury_3488 (Feb 14, 2008 at 1:49 PM):
Sorry for my dreadful typo everyone, I meant the DAWN spacecraft, not GAWN (stupid me).

Hyperion is certainly one of the most iregularly shaped objects yet seen closely by spacecraft, with the possible exceptions of asteroids 243 Ida & 433 Eros.

The Neptune moon Proteus is sort of squarish or cuboid with rounded edges, really quite strange.

I forgot the KBO 136108 2003 EL61, a very large 'cigar shaped' icy body (1,950 KM x 960 KM).

In addition to 2 Pallas (570 x 525 x 500 KM), we also have 4 Vesta (575 x 560 x 460 KM).

However Hyperion is far more out of round than either 2 Pallas or 4 Vesta. Very interesting topic this & Hyperion remains the largest seriously irregulalrly shaped object yet seen up close (had the Galileo spaceraft launched in May 1986, we would have seen the very large main belt asteroid 29 Amphitrite in close up).
carolyn (CICLOPS) (Feb 14, 2008 at 8:39 AM):
We've been looking into this issue. Proteus didn't immediately come to mind because it is apparently not as irregular as Hyperion, which is dramatically so. So, we've altered the caption to make it more specific and correct. Thanks for pointing this out to us!
Mercury_3488 (Feb 10, 2008 at 9:35 AM):
I think the Neptune moon Proteus is the largest confirmed irregularly shaped object in the solar system.

Main belt asteroid 2 Pallas (570 X 525 x 500 KM) may top Proteus however, we may find out if the GAWN spacecraft gets a 2 Pallas flyby in December 2018, after the primary mission @ 4 Vesta & 1 Ceres is over.
kheider (Feb 10, 2008 at 0:13 AM):
Isn't Neptune's Proteus at 420km in diameter still the largest known irregularly shaped body in the Solar System?
carolyn (CICLOPS) (Sep 30, 2007 at 6:01 PM):
No problem. Just the usual delays in examining the data, determining what we feel confident saying, coordinating this with all the various people on the Project, getting approval from all the various agencies for release of image products and press releases, and on, and on, and on. Doing science isn't like instant replay, you know! Look for something spectacular early in the week of October 8!
sustayne (Sep 21, 2007 at 7:30 AM):
I have come to the site a number of times since the latest Iapetus flyby. I have read about the hundreds of photos taken which are all apparently exceptional to look at. PLease post them soon as well as the radar data. It would be helpful to explain what is taking this long to get more information posted, if there is some sort of problem. Thank you.

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