The Sun's Surface Is 5,500°C. Its Atmosphere Is 2 Million. Nobody Fully Knows Why.
The Sun's surface runs about 5,500°C. Yet the thin outer atmosphere surrounding it, the corona, sits at roughly 2,000,000°C, about 360 times hotter. That backwards physics has stumped scientists for nearly a century, and Parker Solar Probe is now flying straight into the corona to find the culprit.