Spacevidcast 2.24 Newsathon


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  1. Rick Boozer on August 3, 2009 at 5:35 pm


    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 on August 3, 2009 at 7:29 pm

      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:

      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:

      Btw. regarding telescopes and astronomy: I can highly recommend the “Hubblecast” to everyone (remotely) interested in astronomy:

      • Rick Boozer on August 3, 2009 at 10:16 pm


        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.

        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.

      • Rick Boozer on August 3, 2009 at 10:33 pm

        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 on August 3, 2009 at 10:39 pm

          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!

  2. Rick Boozer on August 3, 2009 at 5:59 pm

    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.

  3. Rick Boozer on August 4, 2009 at 5:59 pm


    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.
    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 on August 4, 2009 at 9:09 pm


      • Rick Boozer on August 4, 2009 at 10:10 pm

        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 on August 4, 2009 at 11:13 pm

        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 on August 5, 2009 at 9:13 am

          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:

          The author probably mixed up facts from the new impact with his quote from the SL-9 incident, because the source he provides:

          does not say anything about the size of the impact point.

          In another News from NASA (with the beautiful Hubble WFC3 image) ( ) 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:

          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 on August 5, 2009 at 7:18 pm


            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.

  4. KaiYves on August 5, 2009 at 12:38 am

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

  5. Marcus on August 5, 2009 at 9:18 pm


    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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