Sun-observing spacecraft sheds light on the solar wind's origin
The solar wind is a ubiquitous feature of our solar system. This relentless high-speed flow of charged particles from the sun fills interplanetary space. On Earth, it triggers geomagnetic storms that can disrupt satellites and it causes the dazzling auroras - the northern and southern lights - at high latitudes.
But precisely how the sun generates the solar wind has remained unclear. New observations by the Solar Orbiter spacecraft may provide an answer.
Researchers on Thursday said the spacecraft has detected numerous relatively small jets of charged particles expelled intermittently from the corona - the sun's outer atmosphere - at supersonic speeds for 20 to 100 seconds.
The jets emanate from structures on the corona called coronal holes where the sun's magnetic field stretches into space rather than back into the star. They are called "picoflare jets" due to their relatively small size. They arise from areas a few hundred miles wide - tiny when compared to the immense scale of the sun, which has a diameter of 865,000 miles (1.4 million km).
"We suggest that these jets could actually be a major source of mass and energy to sustain the solar wind," said solar physicist Lakshmi Pradeep Chitta of the Max Planck Institute for Solar System Research in Germany, lead author of the research published in the journal Science.
The solar wind consists of plasma - ionized gas, or gas in which the atoms lose their electrons - and is mostly ionized hydrogen.
"Unlike the wind on Earth that circulates the globe, solar wind is ejected outward into interplanetary space," Chitta said.
"Earth and the other planets in the solar system whiz through the solar wind as they orbit around the sun. Earth's magnetic field and atmosphere act as shields
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