ALMOST-X CLASS SOLAR FLARE: Giant sunspot AR3976 unleashed an M6.7-class solar flare today (1406 UTC), almost reaching category X. The explosion caused a brief shortwave radio blackout over South America, and it might have hurled a CME into space. Confirmation awaits fresh images from SOHO coronagraphs. Stay tuned. Solar flare alerts: SMS Text.
A WARNING FROM THE TREES: How bad can a solar storm be? Just ask a tree. Unlike human records, which go back hundreds of years, trees can remember solar storms for millennia.
Nagoya University doctoral student Fusa Miyake made the discovery in 2012 while studying rings in the stump of a 1900-year-old Japanese cedar. One ring, in particular, drew her attention. Grown in the year 774–75 AD, it contained a 12% jump in radioactive carbon-14 (14C), about 20 times greater than ordinary fluctuations from cosmic radiation. Other teams confirmed the spike in wood from Germany, Russia, the United States, Finland, and New Zealand. Whatever happened, trees all over the world experienced it.
Most researchers think it was a solar storm—an extraordinary one. Often, we point to the Carrington Event of 1859 as the worst-case scenario for solar storms. The 774-75 AD storm was at least 10 times stronger; if it happened today, it would floor modern technology. Since Miyake's initial discovery, she and others have confirmed five more examples (12,450 BC, 7176 BC, 5259 BC, 664-663 BC, 993 AD). Researchers call them "Miyake Events."
Right: The 774-775 AD carbon-14 spike. [more]
It's not clear that all Miyake Events are caused by the sun. Supernova explosions and gamma-ray bursts also produce carbon-14 spikes. However, the evidence tilts toward solar storms. For each of the confirmed Miyake Events, researchers have found matching spikes of 10Be and 36Cl in ice cores. These isotopes are known to trace strong solar activity. Moreover, the 774-75 AD Miyake Event had eyewitnesses; historical reports of auroras suggest the sun was extremely active around that time.
Miyake Events have placed dendrochronologists (scientists who study tree rings) in the center of space weather research. After Miyake’s initial discovery in 2012, the international tree ring community began working together to look for evidence of solar superstorms. Their collaboration is called "the COSMIC initiative." First results published in a 2018 edition of Nature confirm that Miyake Events in 774-75 AD and 993 AD were indeed global. Trees on five continents recorded carbon spikes.
Above: A global map of COSMIC tree ring and ice core measurements [more]
"There could be additional Miyake Events throughout the Holocene" says Irina Panyushkina, a member of the COSMIC initiative from the University of Arizona's Laboratory for Tree-Ring Research. "An important new source of data are floating tree-ring records from Eurasia and the Great Lakes region. These are very old rings that could potentially capture 14C spikes as far back as 15,000 years. Eventually, I believe we will have a complete record of Miyake Events throughout that period."
Four more candidates for Miyake Events have recently been identified (5628 BC, 5410 BC, 1052 C, and 1279 C). Confirmation requires checking trees on many continents and finding matching spikes of 10Be and 36Cl in ice cores. It’s all part of the "slow and systematic process" of radiocarbon tree ring research, says Dr. Panyushkina.
A complete survey of Miyake Events could tell us how often solar superstorms occur and how much peril the sun presents to a technological society. Stay tuned for updates from the trees.
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You can have it for $134.95. The crystal glass cup is decorated with a 3D butterfly and a red rose. There's a matching teaspoon, too! This marvelous Valentine's Day gift comes with a greeting card showing the cup in flight and telling the story of its journey to the stratosphere and back.
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