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SESK: Stuff Everyone Should Know · sesk.info/astro-convective-zone-granulation

What causes the rice-grain pattern called granulation on the Sun's photosphere?

Convection cells: hot gas rises in the bright granules and cooler gas sinks between them.

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  1. Sunspots packed close together
  2. Rising hot gas in convection cells ✔
  3. Shadows cast by the corona

Why: The convective zone is the outer layer of the solar interior. Hot plasma bubbles up, cools at the surface and sinks again, like boiling oatmeal. The bright granules are the rising columns.

Huh, didn't know that: Rising gas in a granule moves at about 2 to 3 kilometers per second.

The dad joke
The Sun's surface looks like boiling oatmeal. It's a very hot breakfast cereal.
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References

Answer: Rising hot gas in convection cells. The convective zone is the outer layer of the solar interior. Hot plasma bubbles up, cools at the surface and sinks again, like boiling oatmeal. The bright granules are the rising columns.

  1. Astronomy 2e, 15.1 The Structure and Composition of the Sun openstax.org/books/astronomy-2e/pages/15-1-the-structure-and-composition-of-the-sun
    The bright granules are columns of hotter gases rising at speeds of 2 to 3 kilometers per second from below the photosphere.
    Checked 2026-10-10.

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