Discovering the Sun’s Mysteriously Hot Atmosphere

Something mysterious is going on at the Sun. In defiance of all logic, its atmosphere gets much, much hotter the farther it stretches from the Sun’s blazing surface.

Temperatures in the corona — the tenuous, outermost layer of the solar atmosphere — spike upwards of 2 million degrees Fahrenheit, while just 1,000 miles below, the underlying surface simmers at a balmy 10,000 F. How the Sun manages this feat remains one of the greatest unanswered questions in astrophysics; scientists call it the coronal heating problem. A new, landmark mission, NASA’s Parker Solar Probe — scheduled to launch no earlier than Aug. 11, 2018 — will fly through the corona itself, seeking clues to its behavior and offering the chance for scientists to solve this mystery.

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