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Thread: Discussion: Cassini Sees Lightning on Saturn

  1. #1
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    SUMMARY: In orbit around Saturn for more than a month now, the Cassini spacecraft has been sending back mountains of scientific data. It's now detected flashes of lightning, a new radiation belt, and a glow around Titan, Saturn's largest moon. The spacecraft's radio and plasma wave science instrument is detecting the lighting, which varies from day to day; a dramatically different situation from what the Voyagers found 20 years ago. The new radiation belt is just above Saturn's cloud tops and extends around the planet, yet the radiation particles are able to "jump over" the planet's rings.

    What do you think about this story? Post your comments below.

  2. #2
    Rod Kennedy Guest
    Now that Cassini is on station at Saturn there will be a choice for those who grow weary of Martian dust bowls.
    For those who are interested in the evolution of the Cassini/Huygens mission, many planetariums are currently running a program called Ring World. It is a good overview of how Cassini arrived at Saturn and what the mission hopes to acomplish. So visit your local planetarium and take in Ring World.

  3. #3
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    I have been looking at the images from the Cassini Huygens site, and the Polar black spot seems to appear in some images and not in others. Is this because of filters or is it a result of the clouds/convection etc etc?

    Also, what are those streaks in the latest images of the skies around Saturn? Not just the BIG one (which I assume is a techblip) but meteor lookalikes.

  4. #4
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    Originally posted by Eric Vaxxine@Aug 6 2004, 12:04 PM
    the Polar black spot seems to appear in some images and not in others. Is this because of filters or is it a result of the clouds/convection etc
    It is because it appears more distinct in some filters rather than others. It has not made any sudden changes while Cassini has been watching it.
    what are those streaks in the latest images of the skies around Saturn? Not just the BIG one (which I assume is a techblip) but meteor lookalikes.
    When cosmic rays hit the camera's CCD straight on the make a star-like defect in the image, and when they hit obliquely, the leave something that looks like a meteor trail. This is explained somewhere on the Cassini web-site. I had the same question, and found the answer there.

    It is possible to use those defects in the raw images to make some kind of cosmic ray count and identify whether there are periods when substantially more of them are hitting the spacecraft.
    Forming opinions as we speak

  5. #5
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    Ahh...that all makes sense, thank you very much.

  6. #6
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    One of the things that impresses me (I'm sometimes easily impressed) is that there is so much that is visible at that distance from the sun. But then it is kind of like old pictures, say watching events from WWII and before, where we who are used to bright color images are left to imagine a world that was almost always experiencing a 'cloudy day'. Yet as with a candle or a fireplace/camp fire, what is in one sense very little light can seem inside the experience as being more than enough. I'd like to see a picture (and if its there I didn't run across it, yet) of the sun from that distance with the camera that is making these shots. I saw some from some other probes and the sun looked about like the brightness of Sirius, as it seemed.

    This story did touch upon something I had asked in some other place. I hadn't heard much about a radiation belt. So there was one, but, of course, it was different.

    I'm sure I'm about to say something stupid (but amateurs are expected to do that now, aren't we?), but I wonder if Saturn's magnetosphere is responsible for: those discharges that jump past the rings and for the phenomena of the rings themselves. I wonder if the rings are in some zone between two strong magnetic fields. Perhaps the presence in the ring material of the iron so relatively abundant in stony materials is being simultaneously pressed and pulled by competing north and south magnetic fields, former moons being ground out into their orbits by competing magnetic hemispheres. The clumpiness, the braided ring, each reflect the dynamics of a slow grinding process not yet brought to a conclusion. Perhaps with the planet's spin there were physical pressures that twisted apart the physical environment that generated the magnetic field. I picture twisting a piece of bread dough in two directions in order to separate them. So a strong mechanical mix of competing forces separated the physical mass upon which the electromagnetic forces were conducted. I remember watching iron filings form along lines of force around a bar magnet. Whether the individual rings are merely where separate moons or captured asteriods once resided or perhaps they are a remnant of a gravitational accretion ring, still the conserving dynamic may be at least in part defined along such lines of magnetic lines of force.

    There may not be much right about my supposition above, however I'm confident that while certainly there's a lot that's wrong with that notion from our earthly perspective of normal, but there's a lot that is not 'normal' from our earthly perspective about a lot of things we glimpse in the broader universe beyond us.

  7. #7
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    ah the thought of lightenig just amazes me. time to start using anothere part of my brain i guess.

  8. #8
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    Speaking of lightening, as I was reading something and pondering the applicability of our protostellar environment with some place like Saturn held up to that yardstick (under a 'star that failed' motiff, and I know there are piles of people that disagree, http://books.nap.edu/books/0309043336/html...70.html#pagetop, Eugene Levy's "Magnetohydrodynamic Puzzles in the Protoplanetary Nebula" isn't discussing Saturn), one of the things discussed was the generation of a magnetic field within the protostellar nebulosity. In that, when I read of the electron flow across the gases, I thought of that picture of the lightening arcing outward. In this case, there is not sufficient energy to melt the interstellar dust accumulating in the accretion disk. Saturn could therefore be too cold (besides insufficiently massive) to more further emulate another massive gas-gathering body about which it orbits. It makes me wonder if the rings weren't so much a destructive result but possibly potentially constructive, yet hampered by a process frozen by its comparatively low energy environment.

  9. #9
    Guest Guest
    Cassini has been great and it's only early days for the mission, there could be much more exciting stuff to come

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