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SESK: Stuff Everyone Should Know · sesk.info/astro-corona-temperature

How hot is the Sun's corona, its outer atmosphere?

A million degrees or more, far hotter than the 5800 K photosphere below it.

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  1. About 5800 K, like the surface
  2. About 3800 K, cooler than the surface
  3. A million degrees or more ✔

Why: Oddly, the outer atmosphere is much hotter than the visible surface. The temperature climbs from about 10,000 K in the chromosphere to around a million degrees in the corona.

Huh, didn't know that: The corona extends millions of kilometers out and gives off about half as much light as the full Moon.

The dad joke
The corona is hotter than the surface. Even the Sun has a hot take.
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References

Answer: A million degrees or more. Oddly, the outer atmosphere is much hotter than the visible surface. The temperature climbs from about 10,000 K in the chromosphere to around a million degrees in the corona.

  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 hottest part of the solar atmosphere, which has a temperature of a million degrees or more, is called the corona .
    Checked 2026-10-10.

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