Scientists inch closer to understanding what drives the solar wind

At any given moment, Earth’s closest star belches fast, blisteringly hot particles known as the solar wind into space. But how do those winds begin? A study in Nature Astronomy offers one answer to the question, which has long vexed researchers.

Using new satellite and space telescope observations, scientists discovered complex, weblike plasma structures in the sun’s atmosphere that may drive the phenomenon.

The structures are in the sun’s corona, a wispy, intensely hot area that releases a continual, 1 million mph “wind” of charged particles known as plasma into space. Those particles eventually reach Earth, and the space weather that results can affect satellites and produce phenomena such as the Northern and Southern Lights.

Although scientists know more than ever before about the region, the question of how the solar wind escapes the sun’s atmosphere has long eluded researchers. Seeking answers, scientists used data from the middle corona, which had not been previously imaged.

The ultraviolet imagery was gathered by NOAA’s Geostationary Operational Environmental Satellite. In 2018, special telescopes on board the satellites measured UV radiation emitted by the sun’s hard-to-study middle corona.

Researchers homed in on two coronal holes – short-lived spots of cooler temperatures and fast solar winds that formed near the sun’s equator – in the middle corona. There, they found constantly moving, interwoven, weblike plasma structures above the holes.

Using data from other spacecraft, the researchers then created a model to simulate what was going on in the corona’s magnetic field and plasma. They conclude that the web’s magnetic field draws hot plasma from the middle corona, releasing energy and driving the solar wind.

Although the current study analyzed only two holes from 2018, the researchers say it’s likely a wider phenomenon.

There’s still more to understand about the origin and mechanisms that drive the solar wind. But with the help of future solar observations, they write, it may be possible to “fully close these questions.”