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Scientists Figured Out How the Sun Shoots Plasma Jets

Neutral particles are behind spicules’ spectacular show

smithsonian.com

The sun may seem like a perfectly round orb from our vantage point on Earth, but in reality it’s a ball of roiling gas and plasma. As many as 10 million spicules—random jets of solar material—tear away from its surface at any given time. But how do they do this?

That’s stumped scientists ever since the phenomenon was discovered around 1877. Now, reports The New York Times’ Nicholas St. Fleur, one research team thinks they understand what creates the mysterious bursts: a kind of solar sling shot made possible by neutral particles. The team recently published their findings in the journal Science

Spicules randomly fire off the surface of the sun and can travel as fast as 60 miles a second for distances as long as 6,000 miles. Since these jets come and go so quickly, they’re not easy to observe or study from telescopes on Earth. So to study what causes these flaming jets, researchers created a computer simulation of the sun. In a press release, NASA notes that it took over a year to run the simulation, which used observations from NASA’s IRIS spacecraft and a Swedish telescope in the Canary Islands.

But there was a problem with the solar simulation: It wouldn’t create spicules. As St. Fleur reports, the team eventually realized that they hadn’t incorporated neutral particles—as opposed to the charged particles thought to make up plasma—into the model.

When they allowed for neutral particles, the mechanisms that make spicules possible came into focus. Inside the sun, strong magnetic fields are kept in check by the star’s density and held in place by charged particles. But neutral particles in the sun’s outer atmosphere, or chromosphere, affect the magnetic fields differently. In the less dense chromosphere—and with the help of neutral particles—the magnetic fields straighten out instead of tightening into a knot. That snapping, slingshot-like motion pushes plasma off of the sun’s surface, kind of like the cracking of a whip.

Now that scientists understand that neutral particles create spicules, they can investigate whether they affect other solar processes, like solar winds. Will neutral particles be the key to space weather? That remains to be seen—but whether or not they’re behind other phenomena, they still put on quite a show.   

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