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Fig. 1: The carbon-14 spike can be seen 993-994 CE. Colored points represent a studied region around Sweden (NH0) and Japan (NH2); yellow points represent the Japanese cedar analyzed in the study. [1]

The 993–994 carbon-14 spike was a rapid 0.91% increase in carbon-14 isotope content from tree rings dated 993-994 CE. [2] [3] This event was also confirmed with an associated increase of beryllium-10 in Antarctic ice core samples, supporting the hypothesis that this event was of solar origin. [2] [4] There were several astronomical observations during this time that correspond with the 14C and 10Be spikes, but these texts are few and far between. [4] [5] [6]

In 2021, a scientific paper used the 993–994 carbon-14 spike as a benchmark in dendrochronology (tree-ring studies) to precisely determine that Vikings were present in L'Anse aux Meadows in Newfoundland exactly 1000 years prior, in 1021 AD. [7]

Historical observations

The solar storm hypothesis is heavily supported by several observations of aurora events from late 992 in Korea, Germany and Ireland, usually describing a red sky, presumably because of major auroras. [4] [5] [6] The historical observations do not completely prove the cause of the 993-994 14C spike but show evidence of a strong solar event taking place late 992, as they were recorded within a relatively short time frame. [4] [6]

In the Korean Peninsula, between December 992 and January 993, a text described "heaven's gate" opening one night. [4] [6]

In the Saxony region of present-day Germany in late 992, several aurora observations were made. One set of observations, recorded October 21, 992, noted that the sky reddened three times. [4] Another set of observations, made December 26, 992, mentioned a light as bright as the sun shining for an hour, then reddening the sky, before vanishing completely. [4]

In the Ulster region of present-day Northern Ireland on December 26, 992, texts described the sky as "blood-red" and having a "fiery hue". [4]

Similar events

The 993–994 carbon-14 spike was one of only a few well-documented 14C events. There had been a considerably larger one, the 774-775 carbon-14 spike, which was around 1.7 times as strong than the 993-994 event. [2] Both events also had subsequent 10Be spikes, which further proves that they are from strong solar activity. [5]

See also

References

  1. ^ Miyake, Fusa; Hakozaki, Masataka; Kimura, Katsuhiko; Tokanai, Fuyuki; Nakamura, Toshio; Takeyama, Mirei; Moriya, Toru (2022-07-04). "Regional Differences in Carbon-14 Data of the 993 CE Cosmic Ray Event". Frontiers in Astronomy and Space Sciences. 9: 886140. doi: 10.3389/fspas.2022.886140. ISSN  2296-987X.
  2. ^ a b c Miyake, Fusa; Masuda, Kimiaki; Nakamura, Toshio (2013-06-26). "Another rapid event in the carbon-14 content of tree rings". Nature Communications. 4 (1): 1748. doi: 10.1038/ncomms2783. ISSN  2041-1723. PMID  23612289.
  3. ^ Dee, Michael W.; Pope, Benjamin J. S. (August 2016). "Anchoring historical sequences using a new source of astro-chronological tie-points". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 472 (2192): 20160263. doi: 10.1098/rspa.2016.0263. ISSN  1364-5021. PMC  5014109. PMID  27616924.
  4. ^ a b c d e f g h Hayakawa, Hisashi; Tamazawa, Harufumi; Uchiyama, Yurina; Ebihara, Yusuke; Miyahara, Hiroko; Kosaka, Shunsuke; Iwahashi, Kiyomi; Isobe, Hiroaki (January 2017). "Historical Auroras in the 990s: Evidence of Great Magnetic Storms". Solar Physics. 292 (1): 12. arXiv: 1612.01106. doi: 10.1007/s11207-016-1039-2. ISSN  0038-0938. S2CID  255073793.
  5. ^ a b c Mekhaldi, Florian; Muscheler, Raimund; Adolphi, Florian; Aldahan, Ala; Beer, Jürg; McConnell, Joseph R.; Possnert, Göran; Sigl, Michael; Svensson, Anders; Synal, Hans-Arno; Welten, Kees C.; Woodruff, Thomas E. (2015-10-26). "Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4". Nature Communications. 6: 8611. doi: 10.1038/ncomms9611. ISSN  2041-1723. PMC  4639793. PMID  26497389.
  6. ^ a b c d Stephenson, F. Richard (2015-03-15). "Astronomical evidence relating to the observed 14C increases in A.D. 774–5 and 993–4 as determined from tree rings". Advances in Space Research. 55 (6): 1537–1545. doi: 10.1016/j.asr.2014.12.014. ISSN  0273-1177.
  7. ^ Kuitems, Margot; Wallace, Birgitta L.; Lindsay, Charles; Scifo, Andrea; Doeve, Petra; Jenkins, Kevin; Lindauer, Susanne; Erdil, Pınar; Ledger, Paul M.; Forbes, Véronique; Vermeeren, Caroline; Friedrich, Ronny; Dee, Michael W. (2022-01-20). "Evidence for European presence in the Americas in ad 1021". Nature. 601 (7893): 388–391. doi: 10.1038/s41586-021-03972-8. ISSN  0028-0836. PMC  8770119. PMID  34671168.
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