Cometwatch 27 November

This week’s Cometwatch entry was taken by Rosetta’s NAVCAM on 27 November 2015 when the spacecraft was 124 km from the nucleus of Comet 67P/Churyumov-Gerasimenko.

The image scale is 10.6 m/pixel and the image measures 10.8 km across. The contrast has been lightly enhanced to bring out the comet’s activity without losing details of the nucleus.

Single frame enhanced NAVCAM image of Comet 67P/C-G taken on 27 November 2015. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Single frame enhanced NAVCAM image of Comet 67P/C-G taken on 27 November 2015. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

The image shows a beautiful view of Imhotep on the comet’s large lobe, but with the resolution of NAVCAM at this distance it is not possible to make out the same level of detail as seen in the OSIRIS images depicting changes in the smooth, central portion that were observed in this region before perihelion.

Perhaps the most eye-catching features of the image are the two groups of jets fanning out from the comet’s top-right horizon. Less defined jets can also be seen all around the sunlit horizon. The silhouette of the comet’s small lobe is also visible against the background ‘glow’ of activity towards the bottom left of the image.

The original 1024 x 1024 pixel image is provided below:




  • logan says:

    Wanting to signal [again] lack of ‘columnar’ aspect at the jets, so common last year.

    This perspective and illumination brings back the gem ‘cutter’ visual allegory. As if Ducky fractured, more than ‘squashed’ or ‘modeled’.

    This view is also totally new!

    [/very small font] Emily is using ‘glow’ word 🙂

    Suspect changes at the zone of the big outburst. Being perspective new, can’t be sure.

    Emily jet groups adds to surface sources confirmations.

    OSIRIS is going to bring us ‘growing’ images.

  • Clive Hartland says:

    I am intrigued by the gas/dust jets and wonder what the impetus factor is with the Comet.
    Do they have any effect on the travel of the Comet?


    • Gerald says:

      Yes, some.
      To the rotation, and to the trajectory. But still within bounds having allowed Rosetta to predict the trajectory well enough during hybernation.

  • logan says:

    Imhotep now looks like another place!

  • logan says:

    Could any Soul with better sight point to former Imhotep ‘low lands’?

  • Kamal says:

    A new perspective of Imhotep, looking less flat and with more boulders into the distance.

  • originalJohn says:

    Also, emily, a boundary layer, following the edge profile of the nucleus and some tens of metres in depth. Most noticeable at the top left edge.
    Have the investigators commented on this and to what do they attribute it.
    Any data on the jets? Temperature? ion content? ions/neutrals ratio? oxygen content? formaldehyde content? atomic hydrogen content? carbon content? CO/ CO2 ratio?

  • Dave says:

    its a nice picture, but does any one know why we seem to have amountain with a crator on the top of it at the top of the picture.
    Does any body understand why this feature is not sublimating?
    Presumeably its loosing material from the edges ie the clifts are receding but why has it been left standing?


    • logan says:

      Indeed, Dave. At this particular perspective and illumination, Upper Left Border of basin seems to ‘draw’ an arc, around your signaled structure.

    • Kamal says:

      Dave: I don’t know if it is sublimating, but it seems to be active in Gerald’s highlighting of the 22 November picture ( If my identification of the Apis slab in that picture is correct, below it there is an area in shadow which seems to be steaming away.

  • Kamal says:

    Logan: Peak at top is Apis. Right hand side is Khepry. We haven’t seen these parts from this angle before. Lower left is Ash. Boulder group to the left has Cheops. The two boulders to the right is where we had the action in June-July. One of them is I think the one I once designated as being “like a frog”.

      • logan says:

        Angular change in perspective really trick me, Kamal. This challenge should not be a mayor one for pilots and artists among us. Doubting if I am able to make the before/after pairings needed for comparison work. Bill Harris pairings being of great help.

    • logan says:

      Thanks Kamal 🙂 “One of them is I think the one I once designated as being “like a frog”. And myself confusing with Cheops, then… 🙂

      ‘Stirring’ down from Apis is a zone I speculated having glacier morphology and kinetics. Big changes there.

      Using Imhotep as a clock could bet ‘flow’ at the border, -find it unusual- 4 o’clock.

      Thanks to H. NAVCAM and H. ESAC Teams having the means for before/after comparatives, still not the clarity of mind.

      No doubt comets are fragile once coming near a Star.

      • Kamal says:

        As Emily suggests, an Osiris image will show the changes clearly. I can see a few but hard to be sure at this resolution.

  • logan says:

    As commented by De Sanctis, Ceres is exhibiting kind of a cometary behavior at surface.

    Just by accepting accretion disks lower on the scale [and accretion disks around accretion disks], scenarios like this one could be possible.

  • logan says:

    Robin would be surprised of ‘haze’ as near as an asteroid belt object 🙂

  • logan says:

    From the abstract: “…Our investigation indicates that a production rate of O2 of 3.7 ± 1.7% with respect to water is indeed compatible with the obtained Halley data and therefore that O2 might be a rather common and abundant parent species…”

    From our same Team: M. Rubin, K. Altwegg, E. F. van Dishoeck, and G. Schwehm.

    Revisionism 🙂 Happy about that… Congratulating Investigators.

    “…One possible explanation offered by the scientists is that the O2 has already been formed through IRRADIATION OF ICES in the molecular cloud phase and the oxygen remained trapped BEFORE the comet eventually formed…”

    Caps are mine 🙂

    To the Team Water precedes 02, as is ALSO the argument at Ducky’s immediate envelope -perihelion epochs.

    • logan says:

      ERRATA, says: “as is ALSO the argument at Ducky’s immediate envelope -perihelion epochs.” Should say:

      “as is ALICE Team argument at Ducky’s immediate envelope -perihelion epochs- for IONIC Oxygen.


      Could it be that most of water depart from surface as ice grains, at 67P?

    • logan says:

      Chewing this trough several Stellar cycles… This molecular 02 from molecular H20 argument could be as consequence of estimating ion populations, at Mother Clouds. No doubt other reaction chains also plausible 🙂

    • logan says:

      Should be noted Team is talking of IRRADIATED, CRYSTAL FRAMED, ICES. Maybe crystalline ice itself. [Please correct me, if too wild speculation].

      In order to really trap oxygen molecules, for the billions of years.

      Thus, they are talking of certain, formative temperatures… Not the coldest ones, for the O2 traps.

      Any Soul with access to the Paper?

      • logan says:

        ERRATA. Should say: “…Maybe crystalline water itself.”

        • logan says:

          Gosh! This is too much ‘bio’…

          • logan says:

            On evolving on this: The trap is a very good physical one. Not so, biologically speaking.

            The excruciating feeling is that the building blocks are All there, so close, almost together. At sempiternal pause.

            As is life an opportunity chaser.

      • logan says:

        Remember Antarctic Research about ancient atmospheres?

      • logan says:

        Crystals ‘warm’ growed ’60-90K?’ Around a ‘seed’?. Deposed/adhered to additional ‘warm’ mineral condensates. Then accreted into grains. Then cold stored, for Eons…

        Other scripts could apply 😉

        This is fiction.

        • logan says:

          The [apparently omnipresent] story seems to be about time windows, windows of opportunity, of all sizes. How big is ours? Are we really, honestly working at growing our time window?

        • logan says:

          At some no so far time [2 10⁵y] We were decimated to just a bunch of people. [Genetic derive speculate].

        • logan says:

          Indeed we will send eventually colonies to HEO, Moon and Mars. Wiser on the short term is to settle back at desserts, mountains, ices, under ground and under water.

          Humanity need to ‘speciate’. geographically, culturally, socially, technologically… To build resilience.

        • logan says:

          If given the privilege of seeing into the future. This is the humanity I would marvel to see. And not a depressing, fragile ‘mono’ species.

        • logan says:

          What about sending a ‘Water-World’ fully autonomous colony, now? This is serious, Space Research…

  • logan says:

    Beautiful, honest diffusion article on the infancy -ness of Astrochemistry [And the huge advances going on].

    By Clara Moskowitz Senior Editor.

    • logan says:

      —and then they can stick around, even if they are highly reactive. “A molecule can go years and years before it bounces into another molecule in interstellar space,” says Timothy Lee, an astrophysicist at NASA Ames Research Center. “It might be in a region where there’s no radiation, so even if it’s not that stable, it can exist for a long time.”

  • logan says:

    They are looking for Alien Molecules -rightly- at the receding tides of Mother Nebulas…

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