Quick answer · Updated October 2026
How hot is the Sun?
The Sun's visible surface, the photosphere, is about 5,772 K (about 5,500 °C). The core, where nuclear fusion happens, reaches roughly 15 million K. The corona, the wispy outer atmosphere, paradoxically reaches over 1 million K despite being far from the core. The exact mechanism for heating the corona to such extreme temperatures remains one of the biggest open questions in solar physics.
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- The Sun's light is close to white: seen from space it looks white, and it looks yellow from the ground because the air scatters some of its blue light away.
- The corona's temperature paradox is being studied by NASA's Parker Solar Probe, which flies through the corona at up to 692,000 km/h (about 192 km/s).
- Sunspots are cooler regions, around 3,500 K, which is why they look dark in contrast.
- Over the next 5 billion years the Sun will gradually grow hotter and brighter as it ages on the main sequence.
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