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Unusual Charon Closeup

The latest view of Charon shows us a 390-kilometer strip of Pluto’s largest moon with a unique feature, clearly visible below. We are looking at what Jeff Moore (leader of the New Horizons Geology, Geophysics and Imaging team, calls “a large mountain sitting in a moat.” Moore is the first to admit that the scenario has geologists stumped.


Image: This new image of an area on Pluto’s largest moon Charon has a captivating feature — a depression with a peak in the middle, shown here in the upper left corner of the inset. The image shows an area approximately 390 kilometers from top to bottom, including few visible craters. Credit: NASA-JHUAPL-SwRI.

This view of Charon was taken at approximately 0630 EDT (1030 UTC) on July 14, 2015, about 1.5 hours before closest approach to Pluto, at a range of 79,000 kilometers. Again, notice the lack of craters here, reinforcing what we’re learning about Charon’s relatively young surface. I know we were all curious about Charon from the outset, but I don’t know anyone who thought we would be talking about geologically young features on either of these worlds. We have sharper versions coming — this image is heavily compressed, but the Long Range Reconnaissance Imager (LORRI) on New Horizons will be returning richer data.


Comments on this entry are closed.

  • David A. Hardy July 16, 2015, 16:00

    I think this could be a small body that has ‘landed’ rather than impacted, at quite low speed, possibly into a lake of semi-molten lava at the time.

  • Larry Kennedy July 16, 2015, 16:12

    Looking forward to speculation on this one.

  • ljk July 16, 2015, 16:22

    Where New Horizons may head next:


    Lots of details and images about NH and the Pluto encounter included.

  • Ross Turner July 16, 2015, 16:26

    As pointed out by Gary Moretti, a regular commentator on space.com, could the lack of cratering be due to the location of the objects in the outer solar system, away from the dense layer of inner asteroids and not having a gas giant flinging stones at them? In other words would there have been an early or late heavy bombardment era in the Kuiper belt and beyond? Maybe if they send New Horizons past another KBO, like Eris, we would get a better indication of whether the surfaces of Pluto and Charon are actually new, or just haven’t been hit nearly as often. Maybe it is some combination of the two. The team of scientists isn’t mentioning this so maybe it is obviously not the case that the kbo region objects don’t now and didn’t in the past get hit as often.

  • Churyumov July 16, 2015, 17:41

    It’s fantastic, great, wonderful!My congratulation!

  • Eric Hughes July 16, 2015, 18:31

    I have to say that it looks like a low-velocity, grazing impactor in its own impact crater.

  • Jack Foster Mancilla July 16, 2015, 20:40

    Granted, it is a tiny view, but that image of a mountain in a moat looks to me like the result of a low speed collision of an asteroid into Charon. … More like a merging than a collision.

  • P July 16, 2015, 20:44

    Speculation over at unmannedspaceflight is running riot on this one. :)

    How about this for an idea – warm(er) water ice daipir floated up through the colder crust, sublimating non H2O overburden surrounding at the surface.

    That implies internal heat of course…


  • kamal ali July 16, 2015, 23:37

    Wondering where the heat in Pluto, Charon is coming from.
    Are Pluto/Charon big enough to raise tides in each other??
    Does tidal locking mean they have a circular orbit about the barycenter or can their orbits still be eccentric?

  • JTS July 17, 2015, 1:24

    The relatively large size of Earth’s moon has been considered rare. Does the large size of Charon relative to Pluto suggest otherwise? If so, that would put a little nick in the rare Earth hypothesis (if it is assumed that a large moon is necessary for life, which is debatable).

  • David A. Hardy July 17, 2015, 2:58

    Eric obviously agrees with me! But it still looks as if it landed in semi-molten rock, and perhaps rests on a more solid surface lower down.

  • David A. Hardy July 17, 2015, 8:30

    They orbit a mutual centre of gravity. I suspect that tidal forces are small, but they must exist.

  • Michael July 17, 2015, 9:39

    Could be an impact central peak or feature that has been forced up by heat from within and it now sits on top of a soft support which has allowed the mass to collapse back down pulling the surrounding landscape with it.

  • Harry R Ray July 17, 2015, 9:42

    What REALLY amazes me about this image is that slightly below and just to the right of the structure in question (right at the terminator) there APPEARS(professional geologists:Correct me if I am wrong) to be ANOTHER IDENTICAL structure that is TWICE AS BIG. Unfortunately the far rim of the “moat” in this structure lies beyond the terminator, co confirmation may be pretty dificult. As to what they are: My take is this; the mountains probably formed in a way similar to Ceres’ lone(so far) mountain, but; unlike Ceres, the ground on Charon wasn’t strong enough to support the mountains, so sinkholes opened up, almost completely swallowing them.

  • Alex Tolley July 17, 2015, 15:26

    Someone earlier mentioned that Pluto looked a lot like Triton. The young surfaces of both Pluto and Charon might be for very similar reasons as Triton.
    The “geology” (what is the correct name for these worlds?) is fascinating. Have SciFi authors ever really used the differences in their stories apart from obvious surface features and composition?

  • Jack Foster Mancilla July 17, 2015, 15:52

    Tidal forces are nonexistent, there is no rotation of either body, relative to the other body. They are both tidally locked, both presenting a single face towards each other forever. There is no moonrise on Pluto. There is no deformation of Pluto from the gravity of Charon to create any energy.


    The only possible gravitational effect between the two bodies would be the changing distance of the barycenter, if there is any. Like a supermoon on Earth when our moon is closer than normal.

  • Harry R Ray July 18, 2015, 11:26

    Does anybody know when data related to POTENTIAL magnetic fields around Pluto and Charon are scheduled to be transmitted? The reason why I ask this is: The APPARENT excess internal heat issue would be quickly resolved with stronger than anticipated fields around BOTH worlds( MY expectations are: Pluto; very weak magnetic field, and Charon; no magnetic field at all, but; in my wildest dreams, it could be: Pluto;moderate, and Charon;weak). Here’s why: Pluto and Charon MAY be connected by a FLUX TUBE a la Jupiter and Io. If so, resistance to the electrical current could heat both interiors. There is a hint that this IS the case! Charon’s apparantly “painted” dark pole could be as a result of charged particles spiraling down a flux tube, spraying the surface of Charon, and darkening the pole via chemical reactions. We’ll just have to wait and see if this is the case.

  • ljk July 18, 2015, 16:33
  • ljk July 21, 2015, 21:47

    They did it: New Horizons flies past Pluto

    On Tuesday, NASA’s New Horizons spacecraft flew past Pluto, collecting images and other data that it is slowly returning to Earth. Jeff Foust reports on the celebrations at the Applied Physics Lab that marked the successful flyby and the first look at images that are surprising the mission’s science team.

    Monday, July 20, 2015