Paris (AFP)

The Euro-American Solar Orbiter probe delivered on Thursday the closest images ever taken of the Sun, revealing miniature eruptions called "campfires", which could explain the heating of the solar corona, one of the most mysterious phenomena of our star.

The Solar Orbiter mission, in collaboration with the European Space Agency (ESA) and NASA, launched on February 10 towards the Sun, with ten instruments on board, including six observation telescopes, giving the spacecraft a capacity unique to take pictures of the solar surface.

At 77 million kilometers from the star (about half of the Earth-Sun distance), the first close-up images have highlighted a new phenomenon: "campfires", omnipresent mini-solar flares near the surface, detailed ESA at a press conference.

These "campfires", which until now were not visible in detail, "are small compared to the giant solar flares that we can observe from Earth, millions or billions of times smaller", explained David Berghmans from the Royal Observatory of Belgium, principal investigator of the "Extreme Ultraviolet Imager" (EUI) remote sensing instrument, which took images in extreme ultraviolet radiation.

"The Sun may seem calm at first glance, but when we look in detail we can see these miniature flares everywhere we look," he added.

Scientists still do not know whether these "campfires" are a simple miniature version of large eruptions, or the result of different mechanisms. But theories already claim that they "could contribute to the heating of the solar corona", a phenomenon so far unexplained, explains ESA.

The solar corona, the most extreme layer of the Sun's atmosphere which extends over millions of kilometers in space, in fact exceeds a million degrees while the surface of the Sun reaches "only" 5,500 degrees: this gigantic gap defies the laws of nature, which would like that the more one moves away from a source of heat, the more the temperature drops.

Understanding these mechanisms is considered to be the "Grail" of solar physics, emphasizes ESA.

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