The material appears to be the radioactive remnants of a solar storm that battered the atmosphere.
The type of solar emission discovered in the Greenland ice is a particularly powerful type of solar storm called a solar proton event (SPE), which hit some 2,679 years ago. Occasionally, bursts of charged particles like protons are belched into space-and if pitched Earthward, the powerful surge of energetic particles could trigger massive power outages, discombobulate navigation and communication systems, incapacitate commercial aircraft, and even compromise operations aboard the International Space Station. Sometimes, however - during events known as solar storms, caused by explosions on the sun's surface - this stream of particles turns into a deluge and breaks through that magnetic field. For example, in 1989, a solar outburst blacked out the entire Canadian province of Quebec within seconds, damaging transformers as far away as New Jersey, and almost shutting down US power grids from the mid-Atlantic through the Pacific Northwest. This sets off reactions that raise the production rate of radionuclides - unstable atoms with excess nuclear energy, which include carbon-14, beryllium-10, and chlorine-36.
'That's why we must increase society's protection against solar storms, ' said Prof Muscheler.
Professor Raimund Muscheler from Lund University and his colleagues from Korea, Sweden, United Arab Emirates, Switzerland, the United States, and France analyzed ice cores from Greenland in order to learn more about SPEs.More news: Captain Marvel lands at California Adventure Park ahead of Marvel expansion
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Scientists studying ice almost half a kilometre beneath the surface found a band of radioactive elements unleashed by a storm that struck the planet in 660BC. Spikes in beryllium and chlorine isotopes indicated that, during the seventh century BCE, the world was rocked by a storm that might be among the strongest ever recorded. Evidence of such events is detectable in tree rings and ice cores, potentially giving scientists a way to investigate ancient solar activity. 774-775. The latter is the largest solar eruption known to date.
On the basis of previous events, which have been identified between years 775 and 994, the scientists believe that these outbursts are probably a normal part of the Sun's cycle. "There might be more that we have not yet discovered".
The scientists detailed their findings online March 11 in the journal Proceedings of the National Academy of Sciences.
"We need to search systematically for these events in the environmental archives to get a good idea about the statistics - that is, the risks - for such events and also smaller events".