Recently, scientists in the National Space Science Center (NSSC), Chinese Academy of Sciences, found out the strongest solar particle event in the past 11400 years. Occurred in the January of AD 775, the intensity of the associated solar particles is about 2 times higher than that of the catastrophic 1859 “Carrington Event”, known as the largest solar particle event in the past 200 years and resulted in the failure of the telegraph system all over Europe and North America.
In the recent several years, Japanese, European and Chinese scientists have found a rapid radiocarbon 14C increase of 12‰ in cedar/oak tree rings and coral rings around AD775. Conversations began to buss and Emails to fly, yet the exact origin of this rapid increase remains to be uncertain. Either the supernova or the solar particle event might have caused the major 14C upsurge.
Dr. ZHOU Dazhuang of NSSC’s Space Environment Exploration Laboratory believed that the considerable 14C increase in cedar/oak tree rings and coral rings was due to the strong solar particle events and Coronal Mass Ejections (CMEs) with intense particles emissions. The theoretical research also indicates that strong solar flares and CMEs may produce energetic plasma which explode towards the Earth and may have enough energy and intensity to induce a 14C spike and strong auroras on Earth. Thus, this research group introduced comprehensive approaches of identifying strong historical solar particle event using the rapid 14C increase in tree/coral rings, long duration strong auroras and geomagnetic storms.
Dr. ZHOU’s assertion was well proven by historical records on auroras around AD 775. The white light bands like spread silk in night sky, as recorded in the Old Tang Book, the first classic historical work about the Tang Dynasty, AD 618 to 907; the celestial lights in Italy, in the encyclopedia; and in the heavens a red crucifix, in Britain, in the Anglo-Saxon Chronicle. Therefore, a key evidence of strong solar particle event – the world-wide strong and long duration auroras around AD775 was identified and so, the AD775 super solar particle event was identified.
The radiation of the event was extremely strong, according to Dr. ZHOU, in the low Earth orbit (LEO) and deep space the radiation risk – the probability of life-time fatal cancer and leukemia induced by the radiation may be as high as 100% and, all the space missions must be forbidden during such strong solar particle events. In addition to the radiation risk for astronauts, intense solar particles can also make serious damages to devices of microelectronics and photonics in space, to communications and electric power grids.
The paper entitled Super solar particle event around AD775 was found was published on Chinese Science Bulletin. And further in-depth investigation on the ancient solar activities and space weather deploying the novel approach of science, ancient literature, and archaeology is underway. This discovery and the related investigation are vital and significant for the research on the solar energetic activities, space weather and forecast, radiation of solar energetic particles and protection.
