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Coolest part of the Sun’s surface

Coolest part of the Sun’s surface
Who
sunspots
Where
Not Applicable
When
1500 BC
The Sun’s photosphere is the point at which it becomes opaque and is generally regarded as its "surface". Sunspots form on the photosphere due to magnetic activity and have a temperature of around 3,700K, compared to around 5,700 K for the surrounding photosphere. Sunspots would glow brightly if they could be seen against the background of space.