After 4.5 Billion Years, Sunshine Finally Figured Out

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A giantunderground experiment has given researchers their first glimpse into the heartof the sun and the subatomic particles that shine down on Earth everyday.

Scientistshave long theorized how these particles, called neutrinos,are formed in the solar inferno, but direct proof has been hard to come by.Neutrinos can give scientists a priceless glimpse into the inner workings ofthe sun because they arrive on Earth virtually unchanged from when they leftthe sun's interior.

Princetonresearchers, working at the underground Gran Sasso National Laboratory in Italy, have made the first real-time observations of low-energy solar neutrinos, fundamentalparticles that are created by the roiling nuclear reactions inside the sun and thatstream in vast numbers from the sun's core.

Steps alongtwo of the routes require the presence of the element beryllium, and physicistshave theorized that these steps are responsible for creating about 10 percent ofthe sun's neutrinos.

The GranSasso lab's huge Borexino detector, located more than 0.62 miles (1 kilometer) underground,overcame the limitations and observed the low-energy neutrinos. The results confirmedthe two nuclear steps that involve beryllium, showing that physicistshave been on target at least about those routes to neutrinos.

"Ourobservations essentially confirm that we understand how the sun shines," Calapricesaid. "Physicists have had theories regarding the nuclear reactions withinthe sun for years, but direct observations have remained elusive. Now weunderstand these reactions much better."

Andrea Thompson
Andrea Thompson
Contributor

Andrea Thompson is an associate editor at Scientific American, where she covers sustainability, energy and the environment. Prior to that, she was a senior writer covering climate science at Climate Central and a reporter and editor at Live Science, where she primarily covered Earth science and the environment. She holds a graduate degree in science health and environmental reporting from New York University, as well as a bachelor of science and and masters of science in atmospheric chemistry from the Georgia Institute of Technology.