Space questions, answered
How hot is the Sun?
The Sun's visible surface is about 5,500°C (9,940°F). Its core is far hotter — around 15 million°C — where nuclear fusion happens.
The surface we see, called the photosphere, is about 5,500°C. Oddly, the Sun's outer atmosphere — the corona — is hotter still, reaching over a million degrees, for reasons scientists are still working out.
The real furnace is the core, at roughly 15 million degrees Celsius and immense pressure, where hydrogen fuses into helium and releases the energy that lights the Solar System.
Sources: NASA — the Sun
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