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Given that the Sun is a bit less than 10 light minutes away from Earth, is it correct to assume in principle (I understand actual processes in the core of the Sun make the situation at a photon's emission far more complicated) that the photons that hit a human eyes on a clear day actually departed from the star less than ten minutes ago?

If you don't mind me saying so in a scientific forum, I find this notion (if confirmed) similarly endearing as the other notions that most elementary building blocks (chemical elements) in our bodies stem from bygone distant stars, and that we never see distant parts of the universe (or the Sun, for that matter) as the are "now", just as they were at a certain past distance in time.

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Do you find 8 minutes to be too long or too short? Why? It's like with the sound - it takes some time for the sound to get there (recall thunderstorm after a lightning) but the light is just much faster than the sound. –  Luboš Motl Dec 9 '12 at 19:15
    
The question has potential... try re-phrasing it to clarify what you want to say. –  Sachin Shekhar Dec 9 '12 at 20:09
    
@LubošMotl I find 8 minutes just right. For context: The (endearing) thought came to me when I was looking up to the winter Sun from the rim of a heated outdoor pool. I asked the question here because I wanted to be sure that it's not invalidated by what we know about particle-wave duality or say standing waves (the latter presumably not an issue with light and in a vacuum, but you get suppose you get my drift). Overall, just some sort of reaction between the elements around my body on a clear winter day, a cross-over between Physics and poetric thought in this correspondent's brain :) –  Drux Dec 10 '12 at 7:08
    
@Sachin Shekhar thx & I'll think about it, esp. about a better (more specific) title (suggestions welcome). But then I don't want to go mystical on this because 1) I don't want to and 2) my sense is the moderators would not have it :) –  Drux Dec 10 '12 at 7:10
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up vote 4 down vote accepted

Solar photons arrive to the Earth about 500 seconds after leaving the photosphere. However, the very energetic photons created in the Sun's core take many millions of years to arrive on Earth as they traverse the radiation and convection zones before arriving at the photosphere.

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May I ask an immediate follow-up question pls (can also post it separately): If we plot a graph with average traveling time y for a photon emitted (inside the Sun) at distance x from an observer on earth, what would its shape be? I suppose it would be linear between r and x because constant speed of light in the vacuum. But the overall shape would be dominated by the shape between 0 and (approx.) r because of the order of magnitude of many million years. Is the overall shape 1) unknown at present, 2) some sort of (partially) logarithmic curve, 3) a step function around r, 4) ... ? –  Drux Dec 10 '12 at 7:34
    
I'm pretty sure (from course notes I don't have to hand) that photons take tens of thousands of years to diffuse from the centre of the Sun to the surface, rather than many millions. –  Warrick Dec 19 '12 at 20:42
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@Drux the process is a random walk for the photons. The time depends on both the number of collisions, and the mean-free-path---which both depend on the density. If you assume the sun has constant density (not that bad of an approx.), then the distance traveled depends on the square-root of the number of collisions, which are roughly constant in time. –  zhermes Dec 26 '12 at 21:37
    
Good catch @Warrick, the average travel time for the average photon is closer to 10s-to-100s of thousands of years as you say. The travel time for a photon from the sun's center, will take closer to a few million years. –  zhermes Dec 26 '12 at 21:40
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