Solar Orbiter Beams Back Its First Images of the Sun
Solar Orbiter, a space mission of international collaboration between ESA and NASA, made its first close approach to the Sun in mid-June and captured unique views of the surface of our star.
“These are only the first images and we can already see interesting new phenomena,” said Solar Orbiter project scientist Dr. Daniel Müller, of ESA.
“We didn’t really expect such great results right from the start. We can also see how our ten scientific instruments complement each other, providing a holistic picture of the Sun and the surrounding environment.”
“These unprecedented pictures of the Sun are the closest we have ever obtained,” added Dr. Holly Gilbert, a project scientist for the mission at NASA’s Goddard Space Flight Center.
“These amazing images will help scientists piece together the Sun’s atmospheric layers, which is important for understanding how it drives space weather near the Earth and throughout the Solar System.”
Launched on February 10, 2020, Solar Orbiter carries six remote-sensing instruments that image the Sun and its surroundings, and four in situ instruments that monitor the environment around the spacecraft.
Normally, the first images from a spacecraft confirm the instruments are working; scientists don’t expect new discoveries from them.
But Solar Orbiter’s Extreme Ultraviolet Imager (EUI) returned data hinting at solar features never observed in such detail. At that time, the spacecraft was only 77 million km away from the Sun, about half the distance between Earth and the star.
EUI principal investigator Dr. David Berghmans from Royal Observatory of Belgium points out what he calls ‘campfires’ dotting the Sun in the new images.
“The campfires are little relatives of the solar flares that we can observe from Earth, million or billion times smaller,” Dr. Berghmans said.
“The Sun might look quiet at the first glance, but when we look in detail, we can see those miniature flares everywhere we look.”
The researchers do not know yet whether the campfires are just tiny versions of big flares, or whether they are driven by different mechanisms. 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.
“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 EUI co-principal investigator Dr. Frédéric Auchère, of the Institut d’Astrophysique Spatiale.
“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 Solar Orbiter deputy project scientist Dr. Yannis Zouganelis, of ESA.
Solar Orbiter’s Polarimetric and Helioseismic Imager (PHI) makes high-resolution measurements of the magnetic field lines on the surface of the Sun. It is designed to monitor active regions on the Sun, areas with especially strong magnetic fields, which can give birth to solar flares.
During solar flares, the Sun releases bursts of energetic particles that enhance the solar wind that constantly emanates from the star into the surrounding space. When these particles interact with Earth’s magnetosphere, they can cause magnetic storms that can disrupt telecommunication networks and power grids on the ground.
“Right now, we are in the part of the 11-year solar cycle when the Sun is very quiet,” said PHI principal investigator Dr. Sami Solanki, director of the Max Planck Institute for Solar System Research.
“The PHI instrument is measuring the magnetic field on the surface, we see structures in the Sun’s corona with EUI, but we also try to infer the magnetic field lines going out into the interplanetary medium, where Solar Orbiter is,
” said PHI co-principal investigator Dr. Jose Carlos del Toro Iniesta, from the Instituto de Astrofísica de Andalucía.
The four in situ instruments on Solar Orbiter then characterize the magnetic field lines and solar wind as it passes the spacecraft.
“Using this information, we can estimate where on the Sun that particular part of the solar wind was emitted, and then use the full instrument set of the mission to reveal and understand the physical processes operating in the different regions on the Sun which lead to solar wind formation,” said Solar Wind Analyser principal investigator Dr. Christopher Owen, of the University College London Mullard Space Science Laboratory.
“We are all really excited about these first images — but this is just the beginning,” Dr. Müller said.
“Solar Orbiter has started a grand tour of the inner Solar System, and will get much closer to the Sun within less than two years. Ultimately, it will get as close as 42 million km, which is almost a quarter of the distance from Sun to Earth.”
This article is based on press-releases provided by the European Space Agency and the National Aeronautics and Space Administration.
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