For decades, astrophysicists predicted that a tiny portion of the Sun’s energy—most of which comes from a reaction called the proton-proton chain—comes from a fusion reaction involving carbon and nitrogen. Now, researchers have finally detected the signal of that fusion, Nature reports. Physicists at the Borexino experiment in Italy had previously detected neutrinos—lightweight elementary particles—produced by the Sun’s predominant fusion process, but not the more elusive neutrinos released by the carbon-nitrogen reaction. After years of refining their detector, the researchers last year finally started to detect the elusive neutrinos making their way from the Sun to—and through—Earth. The results, announced this week at the virtual Neutrino 2020 conference, will help astrophysicists understand the structure of the Sun’s core, as well as its early stages of formation.
*Correction, 3 July, 5 p.m.: An earlier version of this story mischaracterized a fusion reaction involving carbon and nitrogen.