Mystery of the sun's mind-bogglingly hot atmosphere may finally be solved

An image of a solar flare emerging from the sun.

A hot mystery on the sun may be close to being solved.

For decades, scientists have been trying to understand why the sun's outer atmosphere is so much hotter than its surface, despite being farther from the core. Whereas the surface, or photosphere, is millions of degrees Fahrenheit, the outer atmosphere is only about 10,000 F (5,500 C).