Sun-observing spacecraft sheds light on the solar wind's origin
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[August 25, 2023]
By Will Dunham
WASHINGTON (Reuters) - 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.
![](http://archives.lincolndailynews.com/2023/Aug/25/images/ads/current/farmers_grain_sda_FAIR_2023.png)
"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 and protects life by blocking harmful particles and
radiation from the sun. But the solar wind continuously propagates
outward from the sun and inflates a plasma bubble called the heliosphere
that encompasses the planets," Chitta added.
The heliosphere extends out to about 100 to 120 times further than
Earth's distance to the sun.
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![](../images/082523PIX/news_k23.jpg)
The sun as seen by the Solar Orbiter
spacecraft in extreme ultraviolet light in this mosaic of 25
individual images taken on March 7, 2023, by the high resolution
telescope of the Extreme Ultraviolet Imager (EUI) instrument. Taken
at a wavelength of 17 nanometers, in the extreme ultraviolet region
of the electromagnetic spectrum, this image reveals the sun's upper
atmosphere, the corona. ESA & NASA/Solar Orbiter/EUI team/Handout
via REUTERS /File Photo
![](http://archives.lincolndailynews.com/2023/Aug/25/images/ads/current/bennet_lda_010722.png)
The data for the study was obtained last year by one of the three
telescopes on an instrument called the Extreme Ultraviolet Imager
aboard the Solar Orbiter, a sun-observing probe built by the
European Space Agency and the U.S. space agency NASA that was
launched in 2020. The Solar Orbiter was about 31 million miles (50
million km) from the sun at the time - about a third of the distance
separating the sun and Earth.
"This finding is important as it sheds more light on the physical
mechanism of the solar wind generation," said solar physicist and
study co-author Andrei Zhukov of the Royal Observatory of Belgium.
The solar wind's existence was predicted by American physicist
Eugene Parker in the 1950s and was verified in the 1960s.
"Still, the origin of the solar wind remains a longstanding puzzle
in astrophysics," Chitta said. "A key challenge is to identify the
dominant physical process that powers the solar wind."
The Solar Orbiter is discovering new details about the solar wind
and is expected to obtain even better data in the coming years using
additional instruments and viewing the sun from other angles.
Zhukov said stellar wind is a phenomenon common to most, if not all,
stars, though the physical mechanism may differ among various types
of stars.
"Our understanding of the sun is much more detailed than the
understanding of other stars, due to its proximity and thus the
possibility to make more detailed observations," Zhukov added.
(Reporting by Will Dunham, Editing by Rosalba O'Brien)
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