The ESA-NASA mission's closest approach to our star yet has yielded new photos.
A spacecraft has observed a spiky "hedgehog" on the sun and a solar flare in previously unseen ways.
The Solar Orbiter, a joint project of NASA and the European Space Agency, launched in February 2020 and is currently circling around our star (SN: 2/9/20). Researchers revealed photographs from the spacecraft's closest solar flyby to date on May 18. On March 26, the orbiter traveled within 48 million kilometers of the sun, putting it closer to the sun than Mercury.
"It's incredible to have this kind of data already," says David Berghmans, a solar physicist at the Royal Observatory of Belgium in Brussels.
Due to its spikes of darker, colder gas above hotter material, the feature has been dubbed the hedgehog. "'Cool' is relative here, in comparison to the 1-million-degree background [plasma]," explains Berghmans, the orbiter's Extreme Ultraviolet Imager's main investigator. Scientists aren't sure what produces this feature, but they believe it has something to do with spicules, which are long, thin jets of solar material (SN: 11/14/19).
Four of Solar Orbiter's instruments spotted an X-ray flare a few days before seeing the 25,000-kilometer-wide hedgehog and investigated how it affected adjacent space. This is exactly what the spacecraft was designed to do, according to Berghmans.
"Connection science" is the goal of the mission, he explains. Over several hours, the Solar Orbiter's instruments identified the solar flare, the shock wave is produced, and the resulting rush of charged particles and radio signals one by one. Previously, these would be detected individually over days by different telescopes.
Scientists may better forecast the discharges of those charged particles, which are extremely threatening to astronauts, satellites, and even high-flying airplanes, by integrating the chain of events into "a full story," according to Berghmans.
By 2026, the spacecraft will fly close to the sun every five to six months. The orbiter will then travel closer to the sun's poles for three more years, giving astronomers their first direct observations of those areas.
European Space Agency. The sun as you’ve never seen it before. May 18, 2022.