A comet tale plus pummeling asteroids leave carbon stains on Vesta

Comet C/2012K5 passes near the bright star cluster M36 in the constellation Auriga the Charioteer last night. The comet is fading now but still visible in binoculars from a dark sky. Details: 200mm lens at f/2.8, ISO 800 and 2-minute exp. Photo: Bob King

Last night I attached my camera to a battery-operated mount designed to track the stars. What a comedy. Polar alignment kept slipping, the camera-lens weight was too much for the mount and focusing the telephoto lens proved tedious. All I wanted was a single picture of comet C/2012 K5. In the end, I got a lot of exercise hopping back and forth making adjustments …  and a somewhat serviceable image.

Up around 6 a.m. this weekend? Look south and you’ll see the last quarter moon pass the bright star Spica in Virgo Saturday and then Saturn on Sunday. Created with Stellarium

The comet had faded a bit but was still a fuzzy blotch in binoculars and showed an obvious northeastward-pointing tail at low magnification through the telescope. Although the tail color was too subtle to be seen with the eye, a time exposure reveals the yellow tint caused by sunlight reflecting off dust particles. Heat from the sun vaporizes comet ice, releasing embedded rocks and dust into the tail behind the comet’s head.

Scene from Yellowknife Bay on Mars photographed today Jan. 4, 2013. Credit: NASA/JPL-Caltech with color added by Bob King

Not much news has been reported from the Curiosity rover of late. NASA mission specialists are probably happy they can work in peace out of the media spotlight. Pictures keep pouring in just the same. You can view the most recent set of raw images HERE.

The rover’s been exploring a shallow basin called Yellowknife Bay. It’s one bleak-looking landscape that begs for the introduction of a few saguaro cacti. After finishing up exploration of the bay, scientist plans to spend most of 2013 piloting the rover toward the mission’s primary science destination – the 3-mile-high layered mound at center of Gale Crater center named Mt. Sharp. There the robot will study and sample water-rich clays deposited long ago when Mars was a wetter world.

Most of the dark, carbonaceous material on Vesta can be found on the rims of smaller craters (left) or scattered in their surroundings (right). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

A recent paper published in the November-December issue of the journal
Icarus describes the dark splotches of carbon-containing materials exposed along the rims of small craters as well as along the edges of the huge impact craters Rheasilvia and Venenaeia on the asteroid Vesta.

NASA’s Dawn mission to Vesta last year took thousands of photos, some of which show dark patches of carbonaceous (car-bon-NAY-shuss) material that matches the dark, carbon-rich mineral fragments found in Vesta meteorites here on Earth.

Dark materials streak Vesta’s Cornelia crater in this three-dimensional image from Dawn. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“The dark material was most probably delivered during the formation of the older Veneneia basin (large impact crater in Vesta’s southern hemisphere) when a slow impacting asteroid collided with Vesta. Dark material from this two to three billion year old basin was covered up by the impact that Dark material from this two to three billion year old basin was covered up by the impact that subsequently created the Rheasilvia basin,” according to Lucille Le Corre and Vishnu Reddy, lead authors of the study.

In this slice of a Howardite meteorite found in the Sahara Desert, some of the small, dark chips are carbon-rich rocks from an asteroid that collided with Vesta long ago. Howardites and eucrites were blasted from the crust of Vesta by later impacts and arrived on Earth as meteorites. Photo: Bob King

The scientists measured the light from the dark patches on Vesta and discovered they were made of the same material as the dark carbon-rich fragments inside a group of fallen space rocks called eucrites and Howardites.

Asteroids, many of which orbit in the main belt between Mars and Jupiter, come in all flavors. Some are made of bone-dry, rocky materials, others contain clays and water and still others are nearly pure metal. Bashing and smashing into one another they left their marks not only on each other but in the pieces that came (and still come) to Earth.

Read more about the new study HERE.

22 Responses

  1. Bob Crozier

    Another cool post, Bob! I’m glad to see Saturn starting to come back into the night sky. That has been my favorite view in my little telescope… so far anyway. But there are a couple of comets coming that might just

    Question (I have so many! … sorry): In that article about Vesta that you linked here, the authors say that the dark material on Vesta came there from another asteroid slowly crashing into it. And then they say that ” ‘Our analysis of the dark material on Vesta and comparisons with laboratory studies of HED meteorites for the first time proves directly that these meteorites are fragments from Vesta’, says Le Corre.” Isn’t that making a huge assumption? If they know that there was at least one asteroid that was the source of that dark material on Vesta (and I think it would be a much safer assumption to suggest that there are others like it still out there, maybe even many others!), would it not be more likely that these HED (whatever that is) meteorites came from those (or similar) asteroids rather than from Vesta? Again, I know nothing about this stuff, so if my question seems silly, please forgive my ignorance.

    1. Profile photo of astrobob

      No huge assumptions are involved on this one. We know from orbital measurements made by Dawn that the HED (Howardites-eucrites-diogenites) all match the composition of Vesta’s crust. Many of those meteorites also contain carbonaceous fragments that, thanks to recent research, links them directly to the dark exposures of carbonaceous materials on Vesta. Those two links taken together indicate a Vestan origin for the HED clan.

  2. Dan Staley

    Try as I might from a Denver suburb after the skies finally cleared, I couldn’t pick out that comet the last two nights. It was good to get back to familiar patterns in Auriga, but still. Thank you for the foto in lieu of actual photons!

  3. lynn

    Hi Bob
    I think sometimes a lot of question’s people ask is just getting over my head a bit and sometimes a bit hard to understand, so can you answer a few question’s for me please:-
    Bob had said in his comment that there is a couple of comets that might just and that was it a thought there was only the comets that you have been discussing recently, I know there is lots out there or is there more coming soon, I don’t get that comment, and the other one from Dan what is he meaning in lieu of photons, what does that mean? Thanks

    1. Profile photo of astrobob

      Hi Lynn,
      Dan’s referring to the comet C/2012 K5 that passing through Auriga right now. I took a picture of it for today’s blog. Dan’s other comment means that he appreciated the photo of the comet since he didn’t see it himself (ie. he saw no comet light or photons.)

    2. Bob Crozier

      Hi Lynn,

      Sorry! I left that sentence incomplete. (See Bob? You’re not only one skipping words once in a while! I can’t even finish a sentence!) What I meant to say was, ” But there are a couple of comets coming that might just become my favorite views!” I was referring to one scheduled to come shine brightly in March and another that I (and many others) hope will survive its very close whip around the Sun in late November and then shine *very* brightly through December, some have speculated maybe even bright enough to be seen in the daytime for a few days.

      Again, sorry for the hurried and poorly written post! I hope that makes more sense to you (and everyone else) now.

      1. Profile photo of astrobob

        No problemo Bob. I knew the ones you meant. By the way, I’ve delved deeper into the solar system barycenter issue and it’s not quite as simple as we imagined. Most of the time the center of gravity is located within and near the center of the sun because of the competing pulls of planets coming from varied directions. On unusual occasions, when they all line up on one side or at least when the biggest planets line up, the barycenter can move toward the solar photosphere and even a small distance OUTSIDE of the sun – a temporary situation.
        In effect, the other planets make Jupiter play nice much of the time. Seen in isolation, each planet and the sun pivot about their individual barycenters. The Earth-sun center of gravity is deep within the sun about 300 miles from solar center. Jupiter’s is about one solar radius or barely outside the sun.

        1. Bob Crozier

          Ya, I read that today somewhere while trying to sort this out in my head. I guess what I don’t understand about this is how the solar system can seem to be constantly self-balancing, or at least that is what this barycenter concept seems to be saying (or am I missing something?). It seems that this concept says that the Sun is actually pulling (moving) *away* from whatever else is tugging at it always just enough to keep the whole system in balance. How does it do that? Obviously I am misunderstanding something here because that just makes no sense. To my rather uneducated mind, if a tire balancing weight on one of my car’s wheels were to slide out of place towards another weight on that rim, then that whole wheel (the whole system) is going to wobble more and more noticeably the further that weight slides. In this ‘tire system’ analogy, I would picture the weights as being equivalent to planets in the solar system The hub of that wheel (which I would picture as the Sun) does not get physically closer to the weights (the planets) but it does get pulled off of the center of gravity (barycenter) *towards* the weights (that is, the center of the rotation of that tire is now *behind* the hub from the perspective of the weights). And then I try to imagine how that system would work without the steel rim forcing everything to ‘stay put,’ and my mind can’t wrap itself around that. It seems to me like it should just all fly apart. Even if it the whole system were nicely balanced at one point, if it got out of balance even once , how does it ‘self-adjust’ to keep from wobbling itself completely apart or totally crashing in on itself? It is, for now at least, more than I can understand.

          1. Profile photo of astrobob

            The solar system doesn’t fly apart because the sun’s overwhelming gravity holds it all together. The sun contains 99.8% of the total mass of the solar system while Jupiter contains most of the remaining 0.2%. The planets don’t collapse into the center because they possess angular momentum, ie. their outward flight balances the sun’s inward pull. It’s the same reason the space station keeps orbiting Earth. Even though it’s always falling toward the Earth because of our planet’s pull, it stays in orbit because it’s moving fast enough at 17,500 mph to “miss” the ground on each revolution and continue on. Unlike the planets, the station feels a slight amount of friction due to a very tenuous amount of atmosphere at its altitude. This slows the station down over time, lowering its orbit. To correct the problem, the astronauts periodically have to fire the engines to boost its orbit.

  4. lynn

    Aww thanks Bob, your a wee gem :-), my head has had a lot of things to take in recently from you, Georgio and the other Bob lol but has all been very educational. Thanks to you all

  5. lynn

    Sorry its me again Bob, but I probably never asked this to you very well, I know you answered me about Dan’s comments, but what was Bob talking about as he had said there is a couple of comets coming that might just? What does that mean, is there more comets coming or was that just a statement, hope you can help as I thought you had answered that to me but it was just Dan’s you had said about, hope you know what he meant.

  6. vincenzo

    Hi Bob, great shot of K5 ! I think I saw it, barely, the other night (3 Jan at about 9pm UT) just to the upper right of the 6th mag star just below M36 (referring to your gorgeous photo). I did not see much of a nucleus, just a fuzzy-ish cloud where there was supposed to be nothing… I have a 4.5 inch and the sky suffered of the glow of Rome, Italy, to the immediate south..

    1. Profile photo of astrobob

      Thank you and congratulations on spotting K5. That’s exactly how it would be appear in a 4.5 inch. The tail might be visible from a dark sky in a scope that size.

    2. Giorgio Rizzarelli

      Same here Vincenzo fellow Italian (I live in Trieste). Being busy I wasn’t able to go in country and tried from city, I got a shy photo of K5, fuzzy with a tail. I associate to the congrats for the great Bob’s shot of the comet.

  7. lynn

    Thanks Bob Crozier, and thanks too Bob, I knew about they comets but I just thought there was another one, it can be sometimes hard to try and work out what other people are talking about, I can do the same thing at times, you know what your talking about but the other person has no clue lol but thanks for clearing that up, I think I maybe stop reading other comments its getting me into bother lol :-)

  8. lynn

    Hi Bob
    I just read on spaceweather.com that there is in fact two meteor showers on the go and an unidentified comet, I was wondering how long does it take for them to work out data about a new comet and does spaceweather update about it when it’s known. Thanks :-)

    1. Profile photo of astrobob

      The Jan. Leonids are a minor shower and one of many minor showers I never mention in the blog because the counts are generally 10 or fewer per hour. The comet associated with the shower has yet to be identified. Sometimes it takes a long time to determine what’s causing a particular shower. The Quadrantid meteor shower that people have been watching for over 150 years only recently had its parent asteroid identified by Dr. Peter Jenniskens in 2003.

    2. Giorgio Rizzarelli

      Two friends of mine saw one each yesterday, incuding a fireball. Obviously in both cases I didn’t see anything for I was busy with aligining scope. Murphy’s law

  9. lynn

    Wow that’s a long time Bob didn’t realise it could be that long, and that’s the reason i’ve not been familiar with the other meteor shower as I do try and take everything in you say, thanks Bob and I’m really sorry i’ve been asking a lot of question’s recently it’s just a lot to take in so thanks for all your patience it’s very appreciated :-)

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