The Sun’s core is the hottest part of the Sun.
But our star’s temperature doesn’t behave as you might expect.
The core is roughly 27 million degrees Fahrenheit
and 10 times more dense than gold.
As you move outward, the layers of the Sun become cooler and less dense.
Something unusual, however, occurs when you reach the outermost layer.
While the surface is around 10,000 degrees Fahrenheit,
the corona – the Sun’s outer atmosphere — is several hundred times hotter.
That’s the opposite of what happens with a fire, when it gets cooler the farther away you get.
Scientists call this the coronal heating problem.
It remains one of the greatest unanswered questions in astrophysics.
The corona extends for millions of miles and continues outward as the solar wind,
which bathes Earth and the entire solar system.
This tenuous region consists of super hot elements such as hydrogen, helium, and iron.
There are a variety of theories for what mechanisms could be adding that extra heat into the atmosphere.
Scientists think it may be the result of the Sun’s convective motion
that acts like boiling water and tangles magnetic fields on the surface.
One theory suggests these tangled fields create small waves
that push particles and heat from the surface into the atmosphere like how ocean waves push surfers.
Another theory suggests small bomb-like explosions from the realignment of the Sun’s magnetic field create heat.
Many scientists think it may be a mix of both.
We’ve studied the corona from Earth and satellites,
but to solve our star’s biggest mystery we have to make direct observations from the region itself.