One of the strongest solar storms ever to be shot toward Earth has left the planet in 660 BCE. According to researchers, based on the traces of the storm, which were obtained both in ice cores and in tree rings, they are blasted. The study was published online on March 11 . Procedure of the National Academy of Sciences .
When the sun's magnetic field shifts, it occasionally releases bursts of charged particles into space. In the most extreme solar storms, so-called proton events, these charged particles are dramatically accelerated by interactions with other solar emissions: solar flares or coronal mass ejections. Even the protective magnetic field of the earth can not distract such fast, high-energy particle currents. The radiation is especially dangerous for modern technologies and astronauts.
It is unclear how often such extreme events occur. They have only been tracking satellites and ground-based instruments for around 70 years. To look further back, researchers are looking for spikes in cosmogenic radionuclides such as carbon-1
In 2017, scientists discovered a sudden peak in the carbon ring of Tree Ring 14, which occurred about 660 BC. Dated. that could indicate a proton event. However, a carbon-14 spike can also signal a supernova or a sunburst.
In the new study, researchers around geologist Paschal O'Hare, then at Lund University in Sweden, examined two Greenland ice cores. O & # 39; Hare, now at Heathgate Resources in Adelaide, Australia, and his colleagues found spikes in beryllium-10 and chlorine-36 at the same time.
The relative frequency of radionuclides in the ice indicated that the 660 BC. The event was about ten times stronger than an event in 1956, the strongest solar storm recorded by instruments. The only known solar storm that rivaled the power of the old storm occurred in the years 774-775, an event that was also recorded in tree rings and ice cores.