The Solar Eclipse Is Causing Weird Changes in the Sun's Magnetic Field
The day has finally come. August 21st, 2017, the great American total solar eclipse. Millions across the country are flocking to bear witness, whether it be with full visibility in prime locations like Tennessee or partial visibility in others, like New York. But there's something else remarkable about the eclipse, apart from the dimming of the sun: experts predict that the corona, the aura of plasma around our Sun (and stars in general), will appear to be very neatly defined into loops, fans, and streamers. These spectacular patterns stem from the visible surface of the Sun (its photosphere) and stay rooted thanks to our star's magnetic field.
So, how exactly is this possible? Why are these loops and lines so perfect and clean-looking? It is certainly perplexing, as the magnetism in the photosphere is often referred to as a "mess." According to solar physicist Amir Caspi of the Southwest Research Institute in Boulder, Colorado, "It's not a static surface like the ground, it's more like an ocean...And not just an ocean. It's like a boiling ocean." Now, because the loops and lines of the corona start out in this "boiling ocean," it would make sense that their roots spiral and twist, "And yet," Caspi says, "these structures in the corona are not tangled and snarled and matted like kelp or seaweed in the ocean. They seem to still be these organized, smooth loops. Nobody understands why."
Scientists are hoping that the eclipse will help to give insight into this mysterious phenomenon. It has been proposed, among other theories, that maybe wave motion in the corona's magnetic field lines help to "untie" and "smooth out" the twists. But there is no conclusion on this theory. It is, however, known that the corona must release energy in some way to smooth these loops.