Spacevidcast 2.24 Newsathon

14 Comments

  • Rick Boozer says:

    Ben,

    Please forgive my astrophysicist self. Even though the scar on Jupiter was the size of Earth, the size of the comet that caused it was much smaller. At most a few miles across. So what hit Jupiter was not nearly as big as Earth, but it hit Jupiter going at a tremendously high velocity and produced an explosion equivalent to thousands of hydrogen bombs!

    As for large telescopes on Earth, the newest ones will be equipped with a computerized system called “adaptive optics” in which computers check the condition of the atmosphere many times per second and warp the telescope’s mirrors to cancel the effects of turbulence caused by the atmosphere. This will allow them to have greater resolution than Hubble. However, Hubble’s observations can never be stopped by cloudy weather.

    • Marcus says:

      Current estimates of the size of the object are in the “perhaps a few hundred meters” range. However the impact energy for even such a “tiny” object is believed to be around 2000 megatons (of TNT), in comparison the atomic bomb dropped on Hiroshima had a blast yield between 13 and 18 kilotons.

      I guess everybody can imagine what would happen if something similar hits Earth.

      Currently the big question is: what exactly hit Jupiter? Here is a nice summary: http://science.nasa.gov/headlines/y2009/03aug_whathitjupiter.htm?list999713

      Regarding adaptive optics: this is actually already installed on some (a couple, lots?) modern, big telescopes. The European VLT in Chile with its four 8 meter mirrors is using adaptive optics for quite some time now and the twin Keck telescopes in Hawaii (10 meters each) use it as well.

      Here is a nice list of existing, under construction as well as proposed/planned large telescopes: http://en.wikipedia.org/wiki/List_of_largest_optical_reflecting_telescopes

      Btw. regarding telescopes and astronomy: I can highly recommend the “Hubblecast” to everyone (remotely) interested in astronomy: http://www.spacetelescope.org/videos/hubblecast.html

      • Rick Boozer says:

        Marcus,

        I was basing my estimate of the size of the object based on similar sized blotches produced by the Shoemaker-Levy 9 Jupiter impacts in the 90s. These had objects were up to 2 km wide. http://en.wikipedia.org/wiki/Shoemaker-Levy_9

        If you have information that is based on later data from this paricular impact, then I bow to that. But its hard to believe that an 18 kiloton Hiroshima-sized blast could make a scar as big as the Earth.

        Yes, I know about the adaptive optics on both the Keck and European telscopes. But I’m talking about even more advanced systems that will be installed in later telescopes such as the 30 meter telescope that will be installed on Mauna Kea Hawaii in the next decade.
        http://www.wired.com/wiredscience/2009/07/thirtymetertelescope/

      • Rick Boozer says:

        I just noticed your said 2000 megatons and were just using 18 kilotons as a comparison. But if you read the Wikipedia article I refer to, you will see that all nine Shoemaker Levy objects produced 6,000,000 megations. Divide that by 9 and you have 666,000 megatons per impact! An they produced Earth sized blotches.

        • Rick Boozer says:

          Meant to say an “average” of 660,000 megatons per impact.

          Guys I just started a new semester of school and I need to stop posting when I’m rushed for time the way I am now!

  • Rick Boozer says:

    Oh Ben, one more thing that I almost forgot.

    For those people who still aren’t convinced about orbital depots, here is a link to a fantastic paper that will tell you everything that you need to know. It is a report that was submitted to the Augustine panel on Friday July 31, the day after the last televised panel meeting.

    http://selenianboondocks.com/wp-content/uploads/2009/07/Depot-Centric_Human_Spaceflight.pdf

  • Rick Boozer says:

    Marcus,

    One more thing I forgot to mention about the adaptive optics system of both the Keck and European VLT is that it only works for taking infrared images! Hubble is primarily a visible light telescope (though it can be used for some infrared imaging). Present day telescopes do not have adaptive optics in visible light! There is one exception, the 200 inch telescope at Palomar is testing a prototype visible light adaptive optics system.
    http://www.astro.caltech.edu/palomar/AO/luckycam.html
    This is the type that I was talking about that will eventually be put on next generation telescopes and possibly retrofitted to the telescopes you mentioned.

    • Marcus says:

      Rick, thank you for all of your replies!

      Unlike you, I’m not an astronomer (I guess having read your ebook does not make me one yet ;)) so there is always a lot for me to learn. For example I didn’t know the sizes and energies of the SL-9 impacts until now. And I was also unaware, that current adaptive optics systems only work for (near-)infrared (wikipedia does not say why though, could you explain to me why this is the case? technical limitations?).

      But regarding the new impact on Jupiter: neither the link to the NY Times from Cariann & Ben, nor my link in my first comment above (where I got the size and megaton estimates from) mention in any way that the plume is as big as earth. If I compare the images to the ones from the SL-9 impacts on wikipedia, than the new one is a lot smaller than the large ones from back then (and only the largest one was as big as earth according to wikipedia). So I really don’t think, that this new object was bigger than a kilometer in diameter.

      • Rick Boozer says:

        Hi Marcus,

        Of course I understand that you are an intelligent amateur in such things and probably know far more than most other people.

        However, I hope you don’t mind if I point out that Ben and Cariann did mention on the show that the scar was as big as the Earth. Ben came to the conclusion that because the scar was as big as the Earth that the object that made it was that big. I was just pointing out that the object that caused the scar was much smaller.

      • Rick Boozer says:

        Oh, I forgot to answer your question.

        Infrared light has much longer wavelengths than visible light. Given this fact, adaptive optical equipment for infrared does not have to be made to as fine a tolerance as adaptive optical equipment for visible light.

        One method that I use that often gives me results that are close to the quality of adaptive optics is to make a number of short exposure images of one object. A few of these exposures almost always occur when the atmosphere is steadier than normal. I keep the sharpest images and throw away the less clear ones. I electronically stack the remaining images to produce one image that is even clearer than the ones that were stacked. This happens because an atmospheric distortion in one part of one of the images is often not on the others and the good parts of the others mask the defect out.

        • Marcus says:

          Rick, thank you for reminding me about the different wavelengths of light. I should have thought about that myself. It is plain obvious now why “simple” adaptive optics only work for infrared wavelengths and I feel a bit stupid for asking now…

          Regarding Jupiter:
          I guess I have found the source for the erroneous statement, that the impact “feature” is the size of earth:
          http://thelede.blogs.nytimes.com/2009/07/21/amateur-astronomer-finds-new-earth-size-impact-mark-on-jupiter/

          The author probably mixed up facts from the new impact with his quote from the SL-9 incident, because the source he provides:
          http://www.nasa.gov/topics/solarsystem/features/jup-20090720.html
          does not say anything about the size of the impact point.

          In another News from NASA (with the beautiful Hubble WFC3 image) ( http://www.nasa.gov/mission_pages/hubble/main/jupiter-hubble.html ) it says:
          “Simon-Miller estimated the diameter of the impacting object was the size of several football fields. The force of the explosion on Jupiter was thousands of times more powerful than the suspected comet or asteroid that exploded over the Siberian Tunguska River Valley in June 1908.”

          Wikipedia already has a whole page on the 2009 impact:
          http://en.wikipedia.org/wiki/2009_Jupiter_impact
          There it is also stated, that the object was probably less then a kilometer in diameter and that the impact spot is about 5000 miles across.

          Please don’t get me wrong, I do not want to be the smart ass here, but I just can’t find any source that is backing up the earth-sized impact statement.

          • Rick Boozer says:

            Marcus,

            I was just responding to what Ben and Carey were saying, part of which was that the blotch was as big as the Earth. My general point to them was that the impacting object was much smaller than the Earth, regardless of the size of the blotch. You’re first response proved my central point, that the impacting object was very much smaller, and I thank for that. Not quite as small as my upper estimate, but that was just an educated guess based on the blotch size that Ben and Cariann were stating.

  • KaiYves says:

    October 31? Nice excuse to dress up like an astronaut for Halloween.

  • Marcus says:

    Rick,

    so basically we can agree on that we were just talking past each other while actually trying to point out (nearly) the same thing? :)

    Btw you have to excuse me now, because I’ll take my crappy 2.4″ refractor and go take a look at Jupiter myself! (of course I won’t be able to see the spot with such an inferior device :( )

    Could somebody please turn of the full moon for an hour or so? ;)

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