First Photos Of Comet ISON From Mars

Two of four images released today of Comet ISON photographed by the orbiting MRO from Mars on Sept. 29. Click to enlarge. Credit: NASA/JPL/University of Arizona

The first pictures of Comet ISON taken by the Mars Reconnaissance Orbiter (MRO) are finally here. That’s it? OK, they’re probably not what we were expecting, but they do give astronomers information about the comet’s size from a different perspective than Earth. Keep in mind that the spacecraft’s cameras were optimized to stare down at the sunlit surface of Mars, not poke around the sky looking for comets.

Two more images of the comet taken by MRO. Credit: NASA/JPL/University of Arizona

Even though ISON was only 8 million miles (12.9 million km) when the pix were shot on Sept. 29, the comet is very faint. According to predictions this puts ISON at the low end of brightness expectations. It also constrains the size of the comet’s nucleus, a key indicator of whether it will survive it fiery brush with the sun late next month. Bigger is better of course!

“The image has a scale of approximately 8 miles (13.3 km) per pixel, larger than the comet, but the size of the nucleus can be estimated based on the typical brightness
of other comet nuclei,” according to today’s press release.

Three more observations of Comet ISON are planned for today and tomorrow.

13 Responses

  1. Edward M. Boll

    I was being optimistic that at perihelion, ISON could just edge the daylight comet of 1882, but this is beginning to look a little more doubtful.

    1. astrobob

      Let’s hope. I don’t see why not although I wonder. If the comet passes really close, MRO might be put into protect mode. Wouldn’t want to damage the camera with comet dust. I don’t know this for a fact though.

  2. Edward M. Boll

    I have not seen Saturn in week or so. It must still be visible to the naked eye now setting 81 minutes after the Sun, and 17 minutes before Venus. In less than 8 weeks, it will be close to Comet ISON. I am still optimistic that at that time ISON will be the brighter of the 2.

  3. Giorgio Rizzarelli

    These pics consolate myself, as my first pic of Ison (from city with Moon, clouds and alt-az mount) aren’t much better 🙂 And it’s good news that the orbiter is not furloughed by the US gov shutdown.

    PS I just checked Nova Del in the C8: respect last week, even more fainter and redder (in agreement with the AAVSO curve). In visual the change is very sensible, both in brightness and color, where the star now appears almost red. The camera (not modified) shows it still purple/magenta, even at low exposition, but more saturated than last week.

    1. astrobob

      Thanks for the report on Nova Del. I caught it last night at 9.1 mag. Its dimming as a dust shell forms.

  4. Edward O'Reilly

    We’re certainly getting some conflicting reports of Ison.Some are pessimistic(although the MRO pics are so grainy that would take them with a proverbial grain of salt,lol) while some reports(from BAA,spaceweather) have Ison brighter than Lovejoy 2011 was at same distance from sun.Also,Yoshida’s latest brightness curve was very optimistic.So,mixed signals.Am not TOO worried yet but hope this doesn’t pull another Kohoutek….

    1. astrobob

      Even if it appears to be only slowly brightening this fall, I’m not too worried. As long as it survives perihelion, we’ll have a very nice comet to view.

  5. Luiz Eduardo

    Hey Astrobob.. Do we have any images of Mars after ison has passed by?
    I think that would be a preview for earth.. This would show if there are comets coming along it.
    Thank you!

    1. astrobob

      Hi Luiz,
      I’m waiting just like you. Surprising that NASA has not published additional photos, though perhaps that’s because of the shutdown.

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