By Phil Plait
Someday an unlucky outburst from our sun could strike Earth and fry most of our electronics—and we’ve already had some too-close-for-comfort near misses.
The sun is ramping up for a big year.
In one sense it already had a big year, thanks to the April 8 solar eclipse. But that was a terrestrial phenomenon. What we’re gearing up for is a decidedly solar one—our star is nearing the peak of its magnetic activity cycle, which means more sunspots, more storms and, potentially, more danger to Earth.
The sun’s magnetic field is generated in its interior, where conditions are so hot that electrons are stripped from their host atoms, forming an ionized gas. A basic law of physics states that moving electric charges generate a magnetic field, and it’s this ionized-gas-induced magnetism that so profoundly affects the sun’s behavior.
Unlike Earth, which has a fairly strong and well-organized magnetic field similar to that of a single gigantic bar magnet, the sun is dominated by countless locally generated fields. Each one shapes its own parcel of the solar interior. The actual dynamics of this magnetism are fiercely complex, but to simplify, you can think of our star’s overall magnetic field strength as waxing and waning over a period of about 11 years—what we call the solar magnetic cycle.
Hot material inside the sun rises to the surface and, once cooled, sinks again in a process called thermal convection, in a very similar way to water in a boiling teakettle. It’s like a conveyor belt for stellar energy and is part of the process by which much of the hellish heat from the solar interior makes its way out of the sun and into space to bring life-sustaining warmth to our planet. The sun’s face is festooned with millions of these ever-changing convection cells; each is accompanied by its own internal magnetic field…
READ FULL ARTICLE HERE… (scientificamerican.com)
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