Why is the Sun’s corona much hotter than its visible surface?
Quick Answer
The corona reaches about 1–3 million K, far hotter than the Sun’s surface at roughly 5,800 K, because magnetic fields dump energy into the upper atmosphere.
The Full Story
The Sun’s visible surface, or photosphere, is about 5,800 K, but the outer corona can reach temperatures of around 1–3 million K. This counterintuitive temperature rise is linked to the Sun’s magnetic field, which twists, reconnects, and releases energy into the upper atmosphere. Waves and magnetic reconnection likely both contribute, although the exact balance is still an active research topic. NASA’s Parker Solar Probe, launched in 2018, was designed in part to help solve this long-standing solar physics puzzle.
Key Facts
YouTube Angle
Suggested video title for this topic:
"The Sun’s outer atmosphere is hotter than its surface—here’s why."
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