On October 9, 2022, a seven minute flash of gamma rays from a massive cosmic explosion burst into the night sky, disturbing it in a new way. Even though the explosion was over one billion miles away, it was the brightest light ever detected in the night sky and lasted for seven hours. In India, lightning detectors were triggered, along with instruments that are usually used for studying solar flares.
Officially named GRB 221009, this flash has picked up the nickname BOAT, for brightest of all time. It probably came from the creation of a black hole, or from a huge dying star that exploded into a supernova. It may have also been both - a supernova that led to the birth of a black hole. It impacted radio communications in the lower ionosphere, which is about 60 to 350 kilometers (37 to 217 miles) above the Earth's surface.
The upper ionosphere, which is 350 to 950 kilometers above the surface (217 to 590 miles), was also affected, according to new research reported in Nature Communications. In the upper ionosphere, radiation from the sun is converted into charged particles, which creates a crucial electric field.
This is also the first time a gamma-ray burst has been detected in this part of the atmosphere. First study author Mirko Piersanti, a researcher at the University of L'Aquila noted that scientists have long debated whether the upper ionosphere can be affected by gamma ray bursts.
This study could help us determine whether future gamma-ray bursts pose a threat. If one happened very close to Earth, like from within the Milky Way for example, it could obliterate the ozone layer, added Piersanti.
The ozone layer is essential to protect life on Earth from the ultraviolet radiation unleashed by the sun, and some scientists have suggested that gamma ray bursts may have been responsible for extinction events.
But we still have a lot more to learn, noted Piersanti. The ionosphere might also be able to absorb all of the gamma rays, leaving Earth unscathed. After all, the planet is hit by an average of more than one gamma-ray burst per day. However, one like BOAT only comes around in an estimated one in 10,000 years.
Sources: Phys.org via AFP, Nature Communications
