7:15 AM (Monday) | *Closest images ever taken of the Sun...new "campfires" phenomenon already revealed*

ESA/NASA's Solar Orbiter is returning its first science data, including images of the Sun taken from closer than any spacecraft in history.

Credits: ESA/ATG Medialab

Overview

The Solar Orbiter spacecraft represents an international collaboration between the European Space Agency (ESA) and NASA and was launched at Cape Canaveral on February 9, 2020 to study our closest star.  The Solar Orbiter completed its first close pass of the Sun in mid-June and took the closest pictures ever from just over 47 million miles away (about half the distance from the Earth to the sun). These images will help scientists better understand the Sun’s many atmospheric layers and how it drives space weather near the Earth and throughout the solar system. Other images from the spacecraft will come later in the mission when the Solar Orbiter is even closer to the Sun.

This series of views of the Sun was captured with the Extreme Ultraviolet Imager (EUI) on ESA/NASA's Solar Orbiter on May 30, 2020. They show the Sun’s appearance at a wavelength of 17 nanometers, which is in the extreme ultraviolet region of the electromagnetic spectrum. Images at this wavelength reveal the upper atmosphere of the Sun, the corona, with a temperature of more than a million degrees. The images also reveal “campfires” on the Sun which are annotated with white arrows.

Credits: Solar Orbiter/EUI Team (ESA & NASA); CSL, IAS, MPS, PMOD/WRC, ROB, UCL/MSSL

Details

The Solar Orbiter carries six imaging instruments, each of which studies a different aspect of the Sun.  While the new images have been taken from the closest ever vantage point, they are not the highest resolution ever acquired. The largest solar telescopes on Earth will always beat the Solar Orbiter on that measure. But the probe's holistic approach, using the combination of six remote sensing instruments and four in-situ instruments, puts it on a different level. According to a senior scientist from the European Space Agency, the "Solar Orbiter isn't going closer to the Sun just to get higher-resolution images: it's going closer to get into a different, less turbulent part of the solar wind, studying the particles and magnetic field in situ at that closer distance, while simultaneously taking remote data on the surface of the Sun and immediately around it for context. No other mission or telescope can do that."

This particular image using the Extreme Ultraviolet Imager has annotation that allows for a size comparison between the Earth (circle) and an example of a recently discovered “campfire” (arrow) on the solar surface.

Credits: Solar Orbiter/EUI Team (ESA & NASA); CSL, IAS, MPS, PMOD/WRC, ROB, UCL/MSSL

Generally, the first set of images from a spacecraft are used to confirm that the instruments are working and scientists don’t usually expect to find new discoveries.  However, the Extreme Ultraviolet Imager (EUI) on the Solar Orbiter has returned data that is already revealing solar features never observed in such detail. Specifically, small hot spots that are being referred to as “campfires” by NASA scientists have been observed in these initial EUI images and they are thought to be “little nephews” of solar flares and “perhaps a billion times smaller”.   It is not clear yet what these ubiquitous “campfires” are or how they correspond to solar brightenings observed by other spacecraft, but its possible they are mini-explosions known as “nanoflares” according to NASA and help to heat the Sun’s outer atmosphere (corona) to its temperature which is 300 times hotter than the solar surface. More analysis will be done on this new “campfire” phenomenon found in these initial images including a precise measurement of their temperatures.

This animation shows a sequence of images from the Polarimetric and Helioseismic Imager (PHI) on ESA/NASA's Solar Orbiter. “PHI” measures the magnetic field near the Sun’s surface and allows the investigation of the Sun’s interior via the technique of helioseismology.

Credits: Solar Orbiter/ PHI Team/ESA & NASA

Another instrument on board the Solar Orbiter is the Polar and Helioseimic Imager (PHI) and it is used to map the Sun’s magnetic field with a special focus on its poles.  It will actually play a more important role later in the mission as the Solar Orbiter gradually tilts its orbit to 24 degrees above the plane of the planets which will result in an unprecedented view of the Sun’s poles. Initial “PHI” imagery data appears to be of top-quality and reveals magnetic structures at the surface. Additional imagery and further analysis will help scientists understand better the magnetic field near the Sun’s surface and allows for examination of the Sun’s interior.

Getting to this point in the Solar Orbiter mission was no simple feat in large part due to complications that arose because of the global coronavirus pandemic.  The virus actually forced mission control at the European Space Operations Center (ESOC) in Germany to close down completely for more than a week.  During this time period, the ESOC staff was reduced to a skeleton crew and this forced some critical operations to be performed remotely for the first time ever. The team adapted and the Solar Orbiter was ready-to-go just in time for its first close pass to the Sun on June 15th.  As it flew to within 48 million miles of the Sun, all ten instruments on board were turned on successfully and the closest pictures ever were taken of our all-important star.

Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com

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