What is the earliest record of a solar storm?
Through analysis of ice cores from Greenland and Antarctica, a research team has found evidence of an extreme solar storm that occurred about 9,200 years ago. What puzzles the researchers is that the storm took place during one of the sun's more quiet phases — during which it is generally believed our planet is less exposed to such events. It is currently believed that solar storms are more likely during the so-called sunspot cycle. Research now shows (Nature Communications) that this may not always be the case for very large storms.
“We have studied drill cores from Greenland and Antarctica, and discovered traces of a massive solar storm that hit Earth during one of the Sun’s passive phases about 9,200 years ago,” Raimund Muscheler, geology researcher at Lund University says in a press release.
The researchers scoured the drill cores for peaks of the radioactive isotopes beryllium-10 and chlorine-36. These are produced by high-energy cosmic particles that reach Earth, and can be preserved in ice and sediment. Cosmogenic radionuclides, such as carbon-14, beryllium-10 and chlorine-36, are produced within the Earth’s atmosphere as a result of the interactions of galactic cosmic rays (GCR) with its constituents and are modulated by the solar and the Earth’s magnetic fields. The enhanced flux of relatively lower energy particles during a solar energetic particle event (SEP) can trigger additional production of cosmogenic radionuclides, leaving an imprint in environmental archives.
