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  1. #11
    Join Date
    Jan 2005
    Location
    Sunny California
    Posts
    455
    How come planets are perfectly spherical? Why aren't they, say, egg-shaped? Any astro-physicists out there?

  2. #12
    Join Date
    Mar 2005
    Location
    Bartow, Florida
    Posts
    861
    According to Proffessor Derek Sears (cosmochemistry), it is caused by the gravitational field, in larger masses, gravity acts like it is coming from the center. The process is called Isostatic Adjustment. In smaller masses, such as asteroids, they have a weaker gravitational field. Also stated, planets are not entirely spherical, the bulge out slightly around the equators.

  3. #13
    Join Date
    Jan 2005
    Posts
    63

    My moon attempt

    Taken w/ Canon G6 in RAW, converted and resized. Can't do much with moon shots without telephoto lens.


  4. #14
    Join Date
    Mar 2005
    Location
    Bartow, Florida
    Posts
    861
    I like the trees in the foreground, very nice touch. Here is my night time attempt. same camera. setting of ISO of 100, Remote shutter release, on tripod . Tv 1/20 f8 5.6 let me know what you think.
    Attached Images Attached Images  

  5. #15
    Join Date
    Mar 2005
    Location
    Near New Orleans
    Posts
    1,264
    Speed up the Shutter a little bit and use Mirror Lockup if your camera supports it. That image looks good just a little blurry.
    .

    Canon EOS 30D | Canon EF-S 10-22mm f/3.5-4.5 | Canon 17-40mm f/4L | Canon 24-105mm f/4L IS| Canon 70-200mm f/4L | Canon Speedlite 430EX + Sto-Fen Omni Bounce | Manfrotto 3001BD & 680B/486RC2 | Hoya Super HMC Pro1 Digital Filters | Hitech ND & GND Filters | Bags > Kata R-103 + Lowepro Nova 5 AW

    RawShooter | premium 2006 > My PBase Gallery

  6. #16
    Join Date
    Mar 2005
    Location
    Bartow, Florida
    Posts
    861
    Thanks Bluedog, i will try it. Hopefully i can continue to improve on this subject.

  7. #17
    Join Date
    Mar 2005
    Location
    College Station, TX
    Posts
    68

    Lightbulb small followup on planet shape...

    as previously stated, planets bulge a little around the middle... they're like fat watermelons. (the darkly green stripy ones that are ALMOST round) the bulge is caused by centrifugal (center-fleeing) forces. those forces are the same ones that keep a yo-yo out at the end of its string, instead of falling to the floor, when you swing it around above your head.

    the equator is moving faster due to rotation about the polar axis than say, greenland or new zealand is. this is a strong enough physical phenomenon to pull against gravity (slightly) on the equator and the surface near it, allowing those parts of the world to get a little further from the center.

    the general sphericality comes from gravitational pull applying equally in all directions from the core of a planet as the planet forms. the bigger it is, the more nearly spherical. furthermore, most planets get enough radiation energy to stay a little "soft" so they're like doughballs rolling around on a table... their softness and the constant rolling action keep them round. if you bake them, and then cool them to solidity, they flatten out into cookies, or biscuits, or asteroids.
    I just want to live happily ever after, every now and then. --Jimmy Buffett

  8. #18
    Join Date
    Mar 2005
    Posts
    216
    Quote Originally Posted by Thalas'shaya
    as previously stated, planets bulge a little around the middle... they're like fat watermelons. (the darkly green stripy ones that are ALMOST round) the bulge is caused by centrifugal (center-fleeing) forces. those forces are the same ones that keep a yo-yo out at the end of its string, instead of falling to the floor, when you swing it around above your head.

    the equator is moving faster due to rotation about the polar axis than say, greenland or new zealand is. this is a strong enough physical phenomenon to pull against gravity (slightly) on the equator and the surface near it, allowing those parts of the world to get a little further from the center.

    the general sphericality comes from gravitational pull applying equally in all directions from the core of a planet as the planet forms. the bigger it is, the more nearly spherical. furthermore, most planets get enough radiation energy to stay a little "soft" so they're like doughballs rolling around on a table... their softness and the constant rolling action keep them round. if you bake them, and then cool them to solidity, they flatten out into cookies, or biscuits, or asteroids.

    what a fantastic piece of information, thanks for that.

    great foto's guys. They def. are getting better!!

    Snaz my pic, although clearly not the best, was taken with my handheld p-600 on max optical zoom(X4). then resized in photoshop.

  9. #19
    Join Date
    Mar 2005
    Posts
    185
    I used prime focus with my Canon Rebel EOS and my Nexstar 80 to capture these images
    Attached Images Attached Images  

  10. #20
    Join Date
    Mar 2005
    Posts
    185
    One more with the same setup
    Attached Images Attached Images  

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