CometWatch – 14 August

Rosetta navigation camera (NAVCAM) image taken on 14 August 2014 at a distance of about 100 km from comet 67P/C-G.

Full-frame NAVCAM image taken on 14 August 2014 from a distance of about 100 km from comet 67P/Churyumov-Gerasimenko. Credits: ESA/Rosetta/NAVCAM

Full-frame NAVCAM image taken on 14 August 2014 from a distance of about 100 km from comet 67P/Churyumov-Gerasimenko. Credits: ESA/Rosetta/NAVCAM



  • raymundo dionicio says:

    That ‘face’ on the left
    continues tricking my mind.

    • Gerald says:

      Looks a bit like Vhewbacca 😉

    • Andrew R Brown says:

      I see it too. Small but very apparent. 😀

    • bv says:

      -my count stands @ 16 faces on the left. 6 qualify as “very small.” I’m confused. Are we only counting human faces?

  • Andrew R Brown says:

    What a stunning image, love the view of the crater on the top of the ‘head’ or smaller lobe.

    If you look carefully, you can see the limb of the smaller lobe in front of the top of the large lobe with the ‘neck’ completely hidden.

    This view is the exact opposite side of the fantastic NavCam image released yesterday.

    This crater has been seen before, but at oblique angles, this face on view is fantastic. 😀

    The crater is terraced, surprising on such a small body. Larger craters on large bodies like 4 Vesta, Rhea, Oberon, the Moon, Mercury, Titan, Ganymede, Mars, Venus, Earth and likely on 2 Pallas, 1 Ceres and Pluto etc, yes as gravity causes slumping of the walls, but a tiny comet? Very interesting.

    The wrinkle on the crater floor and the ice boulders are interesting too.


    • raymundo dionicio says:

      That wrinkle could be formed
      by gas emiting dynamics.
      Some others have a central vertex.

  • William Frankeberger says:

    When can we get some data? Is the comet solid rock? Was Horst Uwe Keller (Max Planck) correct, that “a comet is not really a ‘dirty snowball’ “? (What is the data from CONSERT?) Is the ROMAP working yet? What’s the albedo of the comet? We heard earlier that the comet was sublimating two glasses of water a second; is it is or is it ain’t? But I mean… what is the real data, not theory or assumption or a guess-interpretation. Is there any “interstellar dust”? What minerals are in or on the nucleus?

    • emily says:

      Hi William, we post updates here on the blog when we have them (there were some first detections of dust grains from GIADA last week, for example). Philae lands in November, so we won’t have results from e.g. ROMAP & CONSERT until later.

  • lordjohn says:

    Do we know just how old this comet is? Millions or billions of years?

  • raymundo dionicio says:

    Looking at this sublimation crater on the left, with its central vertex. I imagine it ‘radiating’ gas, like if an antenna it were.

  • Carlos says:

    Only one word: paraeidolia. That’s the trick

  • Pete says:

    Is that an old crater I see before me. Surely a chunk of rock that big would have straight through the comet if it was ‘made of cigarette ash’ on the inside.
    Maybe it’s more substantial than we first thought?

    • raymundo dionicio says:

      I suppose that
      weatherization and mineralization
      coming from inside
      ends creating some kind
      of ‘slight cementing’ in this dust,
      Then you have minute gravity.
      But chimneys should be
      ‘inside’ material formerly.

  • raymundo dionicio says:

    I know NAVCAM
    has full agenda but
    at least some pair
    every day or two should be
    taken in a stereoscopic 14min lapse.

    Make us mortals love NAVCAM

  • Tom says:

    Are you folks holding regular news events to promote your work a And generate public interest? Commenters on this blog are no doubt just the tip of the iceberg. Anyone? Bueller? Bueller?

    • emily says:

      News updates are posted here on the blog and on our ESA news portal ( We also host press events, which are live streamed for all to watch, for key milestones, like the arrival on 6 August, for example. Many of the mission partners and local institutes also organize local outreach events to highlight the mission.

  • bv says:

    The “age” comment fascinates. Meteorites are aged at 4.567 BYA giving a putative Solar System formation age. I’d luv to compare ages & daydream about geneses.
    Also–my count stands @ 16 faces on the left. 6 qualify as “very small.” I’m confused. Are we only counting human faces?

  • Dave says:

    The measurement quoted for density looks unlikely. There does not seem to be a thin crust, we can see this where there are escarpments a couple of 100 meters deep and more. No layering of different substances is visible. It looks like homogenous rock, not sponge, ash or ice. It does not look like a loosely bound conglomeration of ice and dust. So the density that has been quoted looks at least an order of magnetude in error! Even if it was solid ice it looks suspect( appreciating that the pictures do not have much resolution yet)
    Any comments?

    • Marco Parigi says:

      Comets where density has been estimated have come to .6 g/cm^3, which is a fair bit greater than current estimates of C-G of .1 or so. I think what is inside the comet nucleus is quite a bit different to the outside. There must somehow be a lot of empty space inside which is not evident from the outside, given that the density will be considerably less than 1. My bet is that the surface is tarry, covering up the empty spaces underneath.

    • raymundo dionicio says:

      Bread of puff pastry.
      Pan de hojaldre en español.
      Please don’t delete.
      I’m proposing it as a model
      for external sun burned layers.

  • Dave says:

    I agree Pete, clearly it’s much more substantial. The quoted density looks to be at least an order of magnetude too low. When you look at the steep escarpments 200 or more meters high you can see no layering of material, no ice and no dust. It is clearly a homogenous solid lump.

  • rockya says:

    Why is everything in space a weird grey silver color? Or is that just the camera greyscale?

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