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SESK: Stuff Everyone Should Know · sesk.info/astro-radiative-zone-photon-trip

Roughly how long does energy from fusion take to work its way from the Sun's center to its surface?

About 100,000 to 1,000,000 years, because photons keep getting absorbed and scattered.

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  1. About 8 minutes
  2. About 100 years
  3. About 100,000 to 1,000,000 years ✔

Why: In the dense interior a photon travels only a tiny distance before it is absorbed or scattered in a random direction. That random walk takes a very long time. The 8 minutes is the trip from the surface to Earth.

Huh, didn't know that: The layer where energy moves mostly by this slow photon random walk is called the radiative zone.

The dad joke
Light takes ages to leave the Sun. It keeps getting distracted on the way out.
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References

Answer: About 100,000 to 1,000,000 years. In the dense interior a photon travels only a tiny distance before it is absorbed or scattered in a random direction. That random walk takes a very long time. The 8 minutes is the trip from the surface to Earth.

  1. Astronomy 2e, 16.3 The Solar Interior: Theory openstax.org/books/astronomy-2e/pages/16-3-the-solar-interior-theory
    it takes between 100,000 and 1,000,000 years for energy to make its way from the center of the Sun to its surface.
    Checked 2026-10-10.

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