Closest ever images of our sun reveal mysterious ‘campfires’ across its surface

17 Jul 2020

Close-up view of the sun taken by Solar Orbiter. Image: Solar Orbiter/EUI Team (ESA and NASA); CSL, IAS, MPS, PMOD/WRC, ROB, UCL/MSSL

ESA and NASA’s Solar Orbiter spacecraft has published its first images of our parent star, revealing that it is dotted with so-called ‘campfires’.

A series of unprecedented photos of our sun have been released, which will help scientists better understand what drives space weather near the Earth and throughout the solar system. The images were taken by the ESA and NASA satellite Solar Orbiter spacecraft, which has strong Irish connections, within 80m km of the sun. This makes it our closest ever view of our parent star.

Launched in February this year, the spacecraft made its first close pass of the sun in mid-June, despite the challenges of operating it in the middle of the Covid-19 pandemic. A skeleton crew based at the European Space Operations Centre (ESOC) in Germany extensively tested Solar Orbiter’s suite of 10 instruments.

Six of these instruments are for imaging, each studying a different aspect of the sun. However, during testing of the imaging equipment, the ESOC team was amazed to find so early that the Extreme Ultraviolet Imager (EUI) returned data hinting at solar features never before observed in such detail.

Principal investigator David Berghmans, an astrophysicist at the Royal Observatory of Belgium in Brussels, described these features as “campfires”.

“The campfires we are talking about here are the little nephews of solar flares, at least a million, perhaps a billion times smaller,” Berghmans said. “When looking at the new high resolution EUI images, they are literally everywhere we look.”

GIF showing close-ups of the sun.

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

Other discoveries

What these so-called campfires are and how they correspond to solar brightenings seen by other spacecraft are yet to be determined. Theorising, the Solar Orbiter team thinks they could be mini-explosions known as nanoflares. These tiny sparks are thought to help heat the sun’s outer atmosphere, known as the corona, to a temperature 300 times hotter than the sun’s surface.

Solar Orbiter’s ‘Spectral Imaging of the Coronal Environment’ instrument will now be tasked with measuring the temperature of these campfires.

Another discovery made using the Solar and Heliospheric Imager (SoloHi) showed so-called zodiacal light – light from the sun reflecting off interplanetary dust that is incredibly faint. In order to see it, SoloHi had to reduce the sun’s light to one-trillionth of its original brightness.

SoloHi’s project lead, Russell Howard of the US Naval Research Laboratory, said the zodiacal light images taken were “so clean”.

“That gives us a lot of confidence that we will be able to see solar wind structures when we get closer to the sun,” he said.

Colm Gorey was a senior journalist with Silicon Republic