We have never been able to measure the magnetic field at the back of the Sun," Solanki added. "But because Solar Orbiter is at a different angle to the Sun than Earth, we could actually see one active region that wasn't observable from Earth. "Right now, we are in the part of the 11-year solar cycle when the Sun is very quiet," said Sami Solanki, the director of the Max Planck Institute for Solar System Research in Gottingen, Germany, and PHI Principal Investigator. When these particles interact with Earth's magnetosphere, they can cause magnetic storms that can disrupt telecommunication networks and power grids on the ground. It is designed to monitor active regions on the Sun, areas with especially strong magnetic fields, which can give birth to solar flares.ĭuring solar flares, the Sun releases bursts of energetic particles that enhance the solar wind that constantly emanates from the star into the surrounding space. It makes high-resolution measurements of the magnetic field lines on the surface of the Sun. The Polarimetric and Helioseismic Imager (PHI) is another cutting-edge instrument aboard Solar Orbiter. "It's obviously way too early to tell but we hope that by connecting these observations with measurements from our other instruments that 'feel' the solar wind as it passes the spacecraft, we will eventually be able to answer some of these mysteries," said Yannis Zouganelis, Solar Orbiter Deputy Project Scientist at ESA. After many decades of studies, the physical mechanisms that heat the corona are still not fully understood, but identifying them is considered the 'holy grail' of solar physics. Its temperature is more than a million degrees Celsius, which is orders of magnitude hotter than the surface of the Sun, a 'cool' 5500 ☌. The solar corona is the outermost layer of the Sun's atmosphere that extends millions of kilometres into outer space. "These campfires are totally insignificant each by themselves, but summing up their effect all over the Sun, they might be the dominant contribution to the heating of the solar corona," said Frederic Auchere, of the Institut d'Astrophysique Spatiale (IAS), France, Co-Principal Investigator of EUI. There are, however, already theories that these miniature flares could be contributing to one of the most mysterious phenomena on the Sun, the coronal heating. The scientists do not know yet whether the campfires are just tiny versions of big flares, or whether they are driven by different mechanisms. Solar Orbiter takes closest images of the Sun. "The Sun might look quiet at the first glance, but when we look in detail, we can see those miniature flares everywhere we look," Berghmans added. "The campfires are little relatives of the solar flares that we can observe from Earth, million or billion times smaller," said David Berghmans of the Royal Observatory of Belgium (ROB), Principal Investigator of the EUI instrument, which takes high-resolution images of the lower layers of the Sun's atmosphere, known as the solar corona. At that time, the spacecraft was only 77 million km away from the Sun, about half the distance between Earth and the star. The campfires shown in the first image set were captured by the Extreme Ultraviolet Imager (EUI) from Solar Orbiter's first perihelion, the point in its elliptical orbit closest to the Sun. Principal investigator David Berghmans, an astrophysicist at the Royal Observatory of Belgium in Brussels, points out what he calls "campfires" dotting the Sun in EUI's images. The unique aspect of the Solar Orbiter mission is that no other spacecraft has been able to take images of the Sun's surface from a closer distance. Images of the Sun taken with Polarimetric and Helioseismic Imager (PHI) and Extreme Ultraviolet Imager (EUI) of the Solar Orbiter spacecraft are seen in a combination of photographs released by NASA.
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