At the poles, this is known to happen because the magnetic field lines extend straight out into space, like the lines that point straight outward from the ends of a bar magnet. In the sandbox of their simulation, Mikić and collaborators are even able to put solar physics to the test - they noticed, for example, coronal rays extending to the left of the solar disk (highlighted in the blue box in the figure above), which are visually similar to the plumes that burst forth from the Sun’s north and south poles (red arrows). While the simulated Sun isn’t perfect, its decent correspondence to the real Sun gives solar astronomers confidence that they’re on the right track to understanding the physics of the Sun’s outer layers. The results of the computer run were encouraging: The simulated corona has the same broad shape as its real-life counterpart, with a few bold, bright “streamers” of plasma flowing out into space, as well as intervening loops with small-scale structure similar to those of the real Sun. It’s rare to be able to run a simulation and test its results immediately. It’s worth pausing here to emphasize how unusual a study like this is - generally, astronomers study slowly evolving, faraway objects. Left: Alson Wong / S&T Online Photo Gallery, Center, Right: Predictive Science, Inc. (See text below for an explanation of the blue box and red arrows.) Right: The simulation also traced the magnetic field lines emanating from the Sun. (See the Nature Astronomy paper for more images.) Center: This simulated image of the solar corona shows a visualization of the 3D magnetic field, intended to highlight the complexity of the Sun's magnetic field and its intimate connection to visible emission from the corona. It was rotated to match the perspective seen in the simulations. Left: Alson Wong captured this composite image of the solar corona during the August 21, 2017, eclipse from Jackson, Wyoming. They then compared these visualizations to actual images taken by ground-based photographers. Mikić and colleagues put this model to the test last year, when they took observations of the Sun on July 16 and August 11, 2017, and let a NASA supercomputer calculate, according to their model, what the solar corona would look like ten days later, during the August 21st total solar eclipse. Zoran Mikić (Predictive Science, Inc.) and collaborators offer a new model of the Sun’s outer layers that’s up to date with the latest theoretical work on how the interior of the Sun heats and magnetically innervates the corona. Miloslav Druckmüller, Peter Aniol, Shadia Habbal / NASA Goddard, Joy Ng The Once and Future Corona This animation compares a composite image generated from photographs taken on the day of the total eclipse (Aug. developed a numerical model that simulated what the corona would look like during the August 21, 2017, total solar eclipse. Now, solar physicists have shown August 27th in Nature Astronomy that they can accurately predict the appearance of the corona one week in advance - an important milestone on the path to predicting the oncoming solar wind. This type of space weather threatens satellites, electrical grids, and telecommunications networks, so it’s in our best interest to understand it. When the magnetic field, continually pulled and stressed by the Sun’s rotation, erupts, it launches coronal plasma into interplanetary space. Because plasma is made of charged particles, which respond to magnetic influence, the Sun’s magnetic field can twist the corona into loops and bands and prongs. The corona expresses the hidden magnetic angst of the Sun. Ironically, its outermost layer - the corona, an intricate crown of super-heated, diffuse plasma - is the least understood. It’s bright, so there’s no shortage of light to examine it’s nearby, so even small details on its surface are clear and for about twelve hours per day, it faces almost no competition for astronomical attention.īut for all its nearness and brightness, the Sun remains mysterious. The Sun is about as easy to study as any astronomical object could be. Observations confirmed that they got the broad strokes right. Scientists predicted the shape of the solar corona as it would be seen during the August 21, 2017, total solar eclipse.
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