The pictures are in! The first image data from the cameras aboard ESA’s Solar Orbiter were revealed today, July 16 2020, and reveal many features on our Sun we’ve never been able to see before—including small-scale flare activity dubbed “campfires.” (I say small-scale but they’re actually the size of entire countries!)
“The Sun might look quiet at the first glance, but when we look in detail, we can see those miniature flares everywhere we look.”
— David Berghmans, Royal Observatory of Belgium (ROB)
The images were acquired on May 30, 2020, when Solar Orbiter was about halfway between Earth and the Sun. This allowed it to capture data as basically twice the resolution that NASA’s Solar Dynamics Observatory can, resolving features as small as 400 km (248 miles) across. The newly-observed campfires are some of those features.
“The campfires are little relatives of the solar flares that we can observe from Earth, million or billion times smaller,” says 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.
The scientists 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,” says Frédéric Auchère, of the Institut d’Astrophysique Spatiale (IAS), France, Co-Principal Investigator of EUI.
[Editor’s note: although they’ve been nicknamed “campfires,” there is no fire on the Sun. The activity there is a result of nuclear fusion and the structures we see are emissions from hot solar plasma interacting with magnetic fields and the Sun’s immense gravity.]
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.
[Editor’s note: although higher-resolution views of the Sun’s surface have been captured by ground-based telescopes, Solar Orbiter (like SDO) can image the Sun in wavelengths that can’t be seen from Earth’s surface—like these extreme ultraviolet ones.]
“These are only the first images and we can already see interesting new phenomena,” says Daniel Müller, ESA’s Solar Orbiter Project Scientist. “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.”
Featured image: close-up crop of a Solar Orbiter image showing campfires on the Sun with Earth to approximate scale. Credit: Solar Orbiter/EUI Team/ESA & NASA; CSL, IAS, MPS, PMOD/WRC, ROB, UCL/MSSL. Earth image from NASA’s EPIC camera aboard NOAA’s DSCOVR satellite. Edit by Jason Major.