Our sun might not seem as enigmatic as more exotic, distant stars, but it's still a marvelously mysterious miasma of incandescent plasma. And it's certainly worthy of our scientific attention: Curiosity aside, a violent solar event could disrupt satellites and cause $2 trillion in damages for the U.S. alone. Yet, despite living in its atmosphere, we don't understand some of its defining phenomena. For sixty years, we haven't understood why the surface is a cozy 5,500 Celsius, while the halo called the corona—several million kilometers away from the star's surface and 12 orders of magnitude less dense—boasts a positively sizzling 1-2 million Celsius.
To figure out why, NASA needs to fly a little closer to the sun—and touch it.
We know that magnetic reconnection—when magnetic field lines moving in opposite directions intertwine and snap like rubber bands—propels nuclear weapon-like waves of energy away from surface. Meanwhile, magnetohydrodynamic waves—vibrating guitar string-like waves of magnetic force driven by the flow of plasma—transfer energy from the surface into corona. However, without more data, our understanding of phenomena like coronal heating and solar wind acceleration remain largely theoretical...but not for long.