The Closest Image Of The Sun, obtained by the Solar Orbiter probe, revealed multiple solar mini-eruptions, described as “bonfires”, on the surface of our Sun.
Solar Orbiter is an international collaboration between ESA and NASA to study the Sun.
It was launched on February 9 , 2020, and it completed its first near-star move in mid-June.
“These unprecedented images of the Sun are the closest ever obtained,” said Holly Gilbert, project scientist for the mission at NASA’s Goddard Space Center in Greenbelt, Maryland.
“These amazing images will help scientists study the different atmospheric layers of the Sun, which is important in understanding how space weather works near Earth and through the solar system.”
“We did not expect such results so soon,” added Daniel Müeller of ESA. “It is an excellent start for the Solar Orbiter.”
Jumping the pandemic obstacle
Reaching this point was not an easy task. The coronavirus pandemic forced mission control at the Operations Center of the European Space Agency (ESOC) in Darmstadt, Germany to close completely for more than a week.
During the commission (the period of time when each instrument is tested), the ESOC staff was reduced to the basics and indispensable, with essential staff working from home.
“The pandemic led us to perform fundamental operations remotely for the first time,” said Russell Howard, principal imaging researcher at Solar Orbiter.
But the team adapted, even preparing for the unexpected encounter between the orbiter and comet ATLAS’s ion and dust tails in early June .
The spacecraft completed its commission just in time for its first passage close to the Sun, flying over the star some 77 million kilometers with all its instruments activated to take the images that illustrate this news.
The Solar Orbiter carries six imaging instruments, each to study a different aspect of the Sun. Normally, the first images of the spacecraft are to confirm that everything is working correctly; so scientists did not expect new discoveries this time.
However, the ultraviolet instrument (EUI) sent data showing solar characteristics never observed in such detail.
The Closest Image Of The Sun Reveals Bonfires in the Sun
Lead researcher David Berghmans, an astrophysicist at the Royal Belgian Observatory in Brussels, points to what he calls “bonfires” distributed on the surface of the Sun.
“These campfires we are talking about are the little nieces of solar flares, at least a million or even a billion smaller,” Berghmans said. “When we looked at the new high-resolution images of the EUI, they were literally everywhere.”
It is not yet clear what these “bonfires” are or how they correspond to the solar illuminations observed by other ships.
One possible explanation is that they are mini-explosions known as nano-comrades: in theory, tiny but ubiquitous “sparks” that would help heat the Sun’s outer atmosphere, or corona, to its temperature 300 times higher than that of the solar surface.
To know this for sure, scientists need more precise measurements of the temperatures of these bonfires, and fortunately the Solar Orbiter has an instrument to do that, SPICE ( Spectral Imaging of the Coronal Environment ).
“So we are looking forward to our next data set,” said Frédéric Auchère, principal investigator of operations for the SPICE instrument at the Institute for Space Astrophysics in Orsay, France. “We hope then to detect these nano-comrades to determine and quantify their role.”
Closest Image Of The Sun obtained by other instruments also showed promise. For example, the SoloHI ( Solar and Heliospheric Imager ) instrument revealed so-called “zodiacal light” (sunlight reflected in interplanetary dust), a light that is so dim that the bright face of the Sun normally obscures it. To see it, SoloHI reduced sunlight to one trillionth of its original brightness.
“The images produced a perfect, very clean zodiac light pattern,” explained Howard. “This gives us a lot of confidence that we will be able to see the structures of the solar wind in the next close-ups”
On the other hand, the test of the PHI instrument ( Polar and Helioseismic Imager ) was also successful. PHI maps the solar magnetic field, with a special focus on the poles.
Later in the mission, when the Solar Orbiter gradually tilts to a 24-degree orbit above the plane of the planets, this instrument will have its glory day by taking unprecedented views of the Sun’s poles.