Scientists have discovered that sunlight can reach energy levels close to 10 trillion electron volts.
Sunlight may be stronger than previously thought, according to a new study published on August 3 in the journal Physical Review Letters. Using an extremely sophisticated telescope, a research team recorded the highest energy light ever detected from the Sun, reaching nearly 10 trillion electron volts.
High Altitude Water Cherenkov Observatory (HAWC) in Mexico. (Photo: Jordan A. Goodman)
This extremely powerful light takes the form of gamma rays, which have the most energy of any type of wave on the electromagnetic spectrum. Scientists discovered that there are more gamma rays emitted from the Sun than they had previously thought.
“Although the Sun is our closest and most familiar star, it still holds many surprises. This new observation is exciting as the research team has demonstrated that the Sun emits high-energy gamma rays,” commented Brian Fields, an astrophysicist at the University of Illinois, who was not involved in the study.
To measure sunlight, the research team utilized the High Altitude Water Cherenkov Observatory (HAWC), which consists of 300 tanks, each containing 200 tons of water. Situated between two dormant peaks of the Sierra Negra volcano in Mexico, this observatory detects energy signals from gamma rays and cosmic rays, even when their light does not reach the Earth’s surface.
When gamma rays collide with the atmosphere in the stratosphere, they explode into a cascade of subatomic particles, leaving traces that HAWC can detect. From 2015 to 2021, the research team collected data from such events and recorded solar gamma radiation exceeding the 1 trillion electron volt energy mark. “After reviewing six years of data, we were astonished to see this gamma ray for the first time. The Sun cannot emit light at such energy levels,” shared Mehr Un Nisa, a postdoctoral researcher at the University of Michigan.
HAWC enabled scientists to identify solar gamma radiation that is ten times stronger than previous estimates. However, they are still uncertain about how or why the Sun emits gamma rays at such high energy levels.
