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Thread: Question about the behavior of photons leaving the Sun's core

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    Default Question about the behavior of photons leaving the Sun's core



    I've been looking at some videos from the Discovery channel discussing the Sun. We know that it takes light about 8 minutes to reach Earth from the Sun.

    However they mention that it takes a thousand years or some such number for light to go from the core to the Sun's surface. As it travels through the plasma it hits atoms and is randomly redirected and therefore takes a very long time to reach the Sun's surface where it then begins the 8 minute trip to Earth.

    Does light really work that way? I have limited knowledge of how light works from flashlight forums where optical experts sometimes weigh in. I realize that optics and plasma are two different things but in flashlights the rays don't (to my knowledge) get redirected. They get absorbed if they are not the rays getting collimated (by the optic or reflector).

    My question is simply, is that really the way photons behave going from the core to the surface of the Sun?

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    Default Re: Question about the behavior of photons leaving the Sun's core

    Not sure if this will help. But makes for interesting read.

    http://www.google.co.za/url?sa=t&rct...Azvos9RncWe1RQ

    Cheers
    .

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    Default Re: Question about the behavior of photons leaving the Sun's core

    Also looked at this article and it seems to explain a little more.

    http://www.google.co.za/url?sa=t&rct..._xhDvsiUHRMbWw

    Hope this all helps your understanding a little more, I sure learnt a lot from these two articles.

    Cheers
    .

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    Default Re: Question about the behavior of photons leaving the Sun's core

    Excellent read, ty for posting.
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    Default Re: Question about the behavior of photons leaving the Sun's core

    Quote Originally Posted by gcbryan View Post
    I've been looking at some videos from the Discovery channel discussing the Sun. We know that it takes light about 8 minutes to reach Earth from the Sun.

    However they mention that it takes a thousand years or some such number for light to go from the core to the Sun's surface. As it travels through the plasma it hits atoms and is randomly redirected and therefore takes a very long time to reach the Sun's surface where it then begins the 8 minute trip to Earth.

    Does light really work that way? I have limited knowledge of how light works from flashlight forums where optical experts sometimes weigh in. I realize that optics and plasma are two different things but in flashlights the rays don't (to my knowledge) get redirected. They get absorbed if they are not the rays getting collimated (by the optic or reflector).

    My question is simply, is that really the way photons behave going from the core to the surface of the Sun?
    Photons can do one of three things when they hit an atom or surface of atoms - reflect, be absorbed or be transmitted. There is always, in any practical material, some probability of reflection and absorption. There are no "perfect" mirrors. When a single photon encounters a single atom we refer to it as "scattering" rather than reflection.

    You might think of the sun light penetrating the ocean over one of the deep trenches as being similar to a photon in the center of the sun taking a path to the surface.

    Some photons are absorbed and some are scattered. The deeper you go into the ocean, the fewer the photons that have made it that far. And each one has been scattered many times to get there.

    Look at the bottom of a cloud and considered how many times the photons you receive have bounced around going through the cloud.

    Now consider the center of the sun. Most photons generated there don't make it to the surface. Those that do have bounced around many times.
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    Default Re: Question about the behavior of photons leaving the Sun's core

    It is often called the photon "random walk." Which can take hundreds of thousands or even millions of years before reaching the photosphere of a star. This is a good explanation of the process:

    The Random Walk of Photons Inside the Sun

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    Default Re: Question about the behavior of photons leaving the Sun's core

    I like thinking of the inner sun photon trip as a constantly increasing curve, with many many obstructions to hamper even that path. The fact that light curves based on gravitational attraction makes this my goto example
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    Default Re: Question about the behavior of photons leaving the Sun's core

    Quote Originally Posted by bogey View Post
    I like thinking of the inner sun photon trip as a constantly increasing curve, with many many obstructions to hamper even that path. The fact that light curves based on gravitational attraction makes this my goto example
    No, gravitation plays no direct role in this. It isn't affecting the photon. Gravitation is keeping the density so high that photons can only take very tiny steps before being scattered.
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    Default Re: Question about the behavior of photons leaving the Sun's core

    Quote Originally Posted by gcbryan View Post
    I've been looking at some videos from the Discovery channel discussing the Sun. We know that it takes light about 8 minutes to reach Earth from the Sun.

    However they mention that it takes a thousand years or some such number for light to go from the core to the Sun's surface. As it travels through the plasma it hits atoms and is randomly redirected and therefore takes a very long time to reach the Sun's surface where it then begins the 8 minute trip to Earth.

    Does light really work that way? I have limited knowledge of how light works from flashlight forums where optical experts sometimes weigh in. I realize that optics and plasma are two different things but in flashlights the rays don't (to my knowledge) get redirected. They get absorbed if they are not the rays getting collimated (by the optic or reflector).

    My question is simply, is that really the way photons behave going from the core to the surface of the Sun?
    Yes. As others have pointed out it can take light a long time to get out of the Sun. The photons can only take baby steps because the density of matter is high. The mean free path for a photon at the center is about a millimeter. Then it is scattered in a random direction.

    The name for the concept is the Thermal timescale or Kelvin-Helmholtz time scale. For the Sun it isn't 1,000 years, it's more like 30,000,000 years.

    Thermal time scale - Wikipedia, the free encyclopedia

    As the photon gets away from the center there are opportunities for inelastic scattering that degrade the energy spectrum. So the spectrum of photons at the surface wind up with a much lower temperature or average energy than those at the center. That loss in energy is partly responsible for keeping the Sun's matter hot.
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    Default Re: Question about the behavior of photons leaving the Sun's core

    Could I use this as an example?

    If I were standing at the center of four football fields and people were crowded very densely around me but thinning out more toward the edges of the fields and I try to move and am pushed in all different directions by all the people I come into contact with it could take me years to finally arrive at the very edge of the field and escape the crowds.
    Not sure if that even makes any sense. However that in my mind would seem to be what is happening to the photon moving from the suns core to it's surface.

    Cheers
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