https://www.wired.com/story/the-blazing-science-of-this-years-total-solar-eclipse/

Tomorrow afternoon at 12:55 pm ET, a total solar eclipse will streak across lower South America, giving thousands of eclipse enthusiasts—and millions of first-timers—gathered in Chile and Argentina an otherworldly thrill. And it will give scientists the opportunity to study the solar corona in a way only possible when an object the size of the Moon perfectly covers the solar disk. By acting as a filter, this celestial event exposes solar details that are otherwise far too dim and intricate to observe.

These gatherings recur roughly every 18 months, when a total eclipse slashes across Earth’s surface at any number of locations. Some of them last just a few seconds; others stretch up to seven minutes. (You might remember the United States’ own captivating encounter in 2017.) That period of totality has traditionally been the only time when the sun becomes dim enough for its atmosphere to be observed directly. As a result, the scientists who specialize in solar research routinely end up working in odd locations around the world—sometimes even aboard private jets chartered to chase the shadow and stretch out its duration—to dig into the only first-hand coronal science this planet has to offer.