Get out the marshmallows and toasting sticks. The closest images yet taken of the sun show tiny flares dubbed “campfires,” astronomers announced in a news conference on July 16.
The images are the first from Solar Orbiter, a new sun-watching spacecraft that’s a joint project between NASA and the European Space Agency. These never-before-seen campfire flares are “little relatives” of larger solar flares (SN: 9/11/17), powerful magnetic outbursts that shoot bright spurts of radiation into space, said David Berghmans of the Royal Observatory of Belgium in Brussels in a news release.
Campfire flares are a million to a billion times as small as typical solar flares. It’s not clear yet whether the flickers are just scaled-down flares, or if the two phenomena have different driving mechanisms.
Solar physicists think campfires could help explain one of the biggest solar mysteries: why the solar corona, the sun’s wispy outer atmosphere, is millions of degrees hotter than the solar surface (SN: 8/20/17). Together, the small but ubiquitous flares could be a source of energy to the corona that astronomers hadn’t accounted for.
“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 Frédéric Auchère of the Institut d’Astrophysique Spatiale in Orsay, France, in the news release.
Solar Orbiter launched February 9 with a suite of scientific instruments to observe the sun and its surroundings (SN: 2/9/20). The new images were taken May 30 with the Extreme Ultraviolet Imager camera when the spacecraft was 77 million kilometers from the sun, about half the distance from Earth. Berghmans and Auchère are the principal investigators for the orbiter’s ultraviolet camera.
Other spacecraft have swooped closer to the sun; the Parker Solar Probe has gotten as close as 24 million kilometers, and will eventually reach 6 million kilometers from the sun’s surface (SN: 12/4/19). But Solar Orbiter’s new pictures, snapped before the spacecraft was officially taking scientific data, are for now the closest images of the sun taken. Solar Orbiter will study the sun for at least four years starting in November 2021 — ultimately coming within 42 million kilometers of the sun — and will be the first spacecraft to fly over the sun’s poles.