How Ancient is the Sunlight we see? Compute time it takes a photon to randomly walk through the Sun

It takes emerging sunlight 8 minutes to reach us here on earth. But what about making the journey through the Sun to its surface? This video tries to explain how you can calculate how long it takes energy of photons created in deep core of the Sun to make the journey to the solar surface.

0:00 Introduction
1:12 Calculation of time it takes photons to randomly walk through the Sun
17:19 Epilog: some further details

One part of the video is from a course I'm teaching at my university (KU Leuven), you can find full videos for that here:
   • Radiation Processes in Astronomy  

The turbulent "convection" simulation in video is actually not for the Sun, but rather shows the turbulent sub-surface region of a massive and hot O-stars. As compared to convection in the Sun, while the structure of the motions are similar the magnitudes are different, and so is the origin to the motion. Actually, it might even be questionable we should call it convection at all in this case. If you're interested in that little puzzle, here's a recent peer-reviewed paper from my group on the topic: https://ui.adsabs.harvard.edu/abs/202...

And here's our home page for some more nice visualisations:
https://fys.kuleuven.be/ster/research...

Image Credit: NASA, and NASA’s Goddard Space Flight Center / SDO (latter for the nice smiling sun :-)
Sun interior image generated with ChatGPT (OpenAI), 2025. Prompt by Jon Sundqvist.

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Playlist for SUPERSTARS-3D:
   • SUPERSTARS-3D  

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