But in the outermost layer of its atmosphere called the corona, temperatures can reach 100 times higher.
That’s a mystery that has puzzled scientists for decades.
It’s known as the coronal heating problem.
The theories both have holes that don’t line up with observations made by spacecraft and telescopes.
They struggle to explain how the corona can get so hot on their own.
They eventually came crashing back to Earth, burning up in the atmosphere.
