The Brightest Flash in the Night Sky: A Cosmic Phenomenon

On October 9, 2022, the night sky was lit up by the brightest flash of light ever recorded, a massive burst of gamma rays from an enormous cosmic explosion approximately two billion light years away. This event, quickly nicknamed the “BOAT” (Brightest of All Time), not only illuminated telescopes worldwide but also disturbed Earth’s upper atmosphere in a way never before detected.

The BOAT’s Impact on Earth’s Atmosphere

The BOAT’s flash lasted a mere seven minutes, but its afterglow was visible to amateur astronomers for seven hours. It activated lightning detectors in India and triggered instruments typically used to study solar flares. More notably, it affected long wave radio communications in the lower ionosphere, a section of Earth’s upper atmosphere approximately 60 to 350 kilometers above the surface.

For the first time, a gamma-ray burst was observed affecting the upper ionosphere, a region extending from 350 to 950 kilometers above Earth, near the edge of space. This is where radiation from the Sun turns into charged particles that form an important electric field.

A Two-Decade Debate Resolved

Mirko Piersanti, a researcher at Italy’s University of L’Aquila, stated that experts in this field had been debating for two decades whether gamma ray bursts could impact the upper ionosphere. “I think we finally answered the question,” said Piersanti, the lead author of a new study in the journal Nature Communications.

The researchers were fortunate that the Chinese-Italian CSES satellite, equipped with an electric field detector, was precisely in the zone illuminated by the gamma-ray burst 500 kilometers above Earth in the upper ionosphere. “We found a shape in the electric field that had never been observed before,” Piersanti added.

The Potential Threat of Gamma-Ray Bursts

The research will aid scientists in understanding the potential threat that other gamma-ray bursts could pose in the future. The worst-case scenario would be if such a powerful blast came from much closer to home — say, within our own Milky Way galaxy. That could “completely erase” Earth’s ozone layer, exposing everything on the surface to the full might of the Sun’s ultraviolet radiation, potentially wiping out life on Earth.

There has previously been speculation that past gamma-ray bursts could have caused ancient mass extinction events. However, Piersanti emphasized that much remains unknown. It is also possible that the ionosphere would absorb all the gamma rays and “nothing would happen” to those of us on the ground.

The Origin of the Gamma-Ray Burst

Last year’s gamma-ray burst, officially called GRB 221009A, is believed to have been caused by either a massive dying star exploding into a supernova, or the birth of a black hole. Given its immense power, it could also have been both — a supernova explosion leading to the creation of a black hole.

The blast originated from the direction of the constellation Sagitta and traveled an estimated 1.9 billion years to reach Earth.

This cosmic event serves as a reminder of the vast and mysterious universe we inhabit, and the potential impacts these distant phenomena can have on our home planet. As we continue to explore and understand these cosmic occurrences, we gain not only knowledge but also a deeper appreciation for the intricacies of the universe.