15-11-2023 (WASHINGTON) Approximately two billion years ago, in a distant galaxy beyond our Milky Way, a colossal star met its end in a spectacular event known as a supernova. The aftermath of this celestial explosion sent forth an immense burst of gamma rays, the most energetic waves within the electromagnetic spectrum. These waves, having traversed the vast expanse of the cosmos, finally reached Earth last year, causing a significant disturbance in the ionosphere, a layer of the planet’s upper atmosphere comprising electrically charged gases known as plasma.
Researchers disclosed on Tuesday (Nov 14) that this gamma-ray burst, identified as the most potent ever detected, created notable disruptions in Earth’s ionosphere. The ionosphere extends from approximately 50 to 950 kilometers above Earth’s surface, forming the boundary between the vacuum of space and the lower atmosphere.
Detected on October 9, 2022, the gamma rays impacted Earth’s atmosphere for about 13 minutes, as reported by the European Space Agency’s Integral (International Gamma-Ray Astrophysics Laboratory) space observatory and various satellites in close Earth orbit. Mirko Piersanti, a space weather researcher at the University of L’Aquila in Italy and the lead author of the research published in Nature Communications, noted that the gamma rays induced a robust variation in the ionosphere’s electric field, likening it to the effects of a solar flare event.
While solar flares are relatively commonplace and originate from the sun, this gamma-ray burst occurred at an astronomical distance—approximately two billion light-years away. The rays’ journey over such vast expanses underscores how even distant cosmic events can influence Earth. A light year represents the distance light travels in a year, amounting to 9.5 trillion kilometers.
Instruments on Earth recorded that the gamma rays disturbed the ionosphere for several hours, triggering lightning detectors in India. This disruption even reached the ionosphere’s lowest layers. Although this particular gamma-ray burst did not pose any harmful effects on life on Earth, scientists hypothesize that a strong burst originating within the Milky Way and directed towards Earth could potentially pose risks, including mass extinctions, due to the flood of harmful ultraviolet radiation.
However, astronomer and study co-author Pietro Ubertini of the National Institute for Astrophysics in Italy reassured that the probability of such an event is exceedingly low. The study leveraged data from the China Seismo-Electromagnetic Satellite (CSES), also known as Zhangheng, a joint Chinese-Italian mission launched in 2018.
The gamma-ray burst’s effects on the ionosphere were meticulously examined using the Electric Field Detector (EFD) instrument on board the CSES, which provided unprecedented resolution in measuring the electric field. Despite the disturbance occurring in the ionosphere, it went unnoticed by observers on the ground.
“Nobody detected anything, but we don’t know if it could have been possible to see some visible signal looking at the right time at the sky,” Ubertini remarked, emphasizing the subtle and distant nature of these cosmic phenomena.
