In order to recover this information, scientists used measurements of radioactive carbon in
What happens in the sun can be observedonly indirectly. Sunspots, for example, show the degree of solar activity - the more sunspots are visible on the surface of the Sun, the more active the processes taking place inside it.
Despite the fact that sunspots are known fromantiquity, they were only documented in detail after the invention of the telescope, about 400 years ago. Thanks to this, we now know that the number of spots changes according to the eleven-year cycle, and there are also periods of strong and weak solar activity, which also affects the climate on Earth.
However, it was previously difficult to recover howsolar activity developed before the beginning of systematic recordings. An international research team traced the Sun's eleven-year cycle back to 969 using measurements of the concentration of radioactive carbon in tree rings.
To restore solar activity formillennium, researchers used the archives of tree rings from England and Switzerland. These tree rings contain a tiny fraction of radioactive carbon C14, with only one in every 1,000 billion atoms being radioactive.
From the half-life of the C14 isotope, you can derivethe concentration of radioactive carbon present in the atmosphere when the growth ring was formed. Since radioactive carbon is mainly produced by cosmic particles, which are more or less held back from the Earth by the Sun's magnetic field - the more active the Sun, the better it protects the Earth - you can determine solar activity from changes in the concentration of C14 in the atmosphere.
As a result of its work, researchthe group found evidence of unusual solar reactions that occurred in 1052 and 1279. They could seriously disrupt electronic circuits on Earth and on satellites.
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