View source for Astronomy:993–994 carbon-14 spike

{{Short description|Solar storm}}
[[File:Carbon-14 plot, showcasing 993-994 spike.jpg|thumb|'''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.<ref>{{Cite journal |last1=Miyake |first1=Fusa |last2=Hakozaki |first2=Masataka |last3=Kimura |first3=Katsuhiko |last4=Tokanai |first4=Fuyuki |last5=Nakamura |first5=Toshio |last6=Takeyama |first6=Mirei |last7=Moriya |first7=Toru |date=2022-07-04 |title=Regional Differences in Carbon-14 Data of the 993 CE Cosmic Ray Event |journal=Frontiers in Astronomy and Space Sciences |volume=9 |pages=886140 |doi=10.3389/fspas.2022.886140 |issn=2296-987X|doi-access=free }}</ref>]]
The '''993–994 carbon-14 spike''' was a rapid 0.91% increase in [[Physics:Carbon-14|carbon-14]] isotope content from tree rings dated 993-994 CE.<ref name=":1">{{Cite journal |last1=Miyake |first1=Fusa |last2=Masuda |first2=Kimiaki |last3=Nakamura |first3=Toshio |date=2013-06-26 |title=Another rapid event in the carbon-14 content of tree rings |journal=Nature Communications |language=en |volume=4 |issue=1 |pages=1748 |doi=10.1038/ncomms2783 |pmid=23612289 |issn=2041-1723|doi-access=free }}</ref><ref>{{Cite journal |last1=Dee |first1=Michael W. |last2=Pope |first2=Benjamin J. S. |date=August 2016 |title=Anchoring historical sequences using a new source of astro-chronological tie-points |journal=Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences |language=en |volume=472 |issue=2192 |pages=20160263 |doi=10.1098/rspa.2016.0263 |issn=1364-5021 |pmc=5014109 |pmid=27616924}}</ref> This event was also confirmed with an associated increase of [[Physics:Beryllium-10|beryllium-10]] in Antarctic ice core samples, supporting the hypothesis that this event was of solar origin.<ref name=":1" /><ref name=":0">{{Cite journal |last1=Hayakawa |first1=Hisashi |last2=Tamazawa |first2=Harufumi |last3=Uchiyama |first3=Yurina |last4=Ebihara |first4=Yusuke |last5=Miyahara |first5=Hiroko |last6=Kosaka |first6=Shunsuke |last7=Iwahashi |first7=Kiyomi |last8=Isobe |first8=Hiroaki |date=January 2017 |title=Historical Auroras in the 990s: Evidence of Great Magnetic Storms |url=http://link.springer.com/10.1007/s11207-016-1039-2 |journal=Solar Physics |language=en |volume=292 |issue=1 |pages=12 |doi=10.1007/s11207-016-1039-2 |arxiv=1612.01106 |s2cid=255073793 |issn=0038-0938}}</ref> There were several astronomical observations during this time that correspond with the <sup>14</sup>C and <sup>10</sup>Be spikes, but these texts are few and far between.<ref name=":0" /><ref name=":3">{{Cite journal |last1=Mekhaldi |first1=Florian |last2=Muscheler |first2=Raimund |last3=Adolphi |first3=Florian |last4=Aldahan |first4=Ala |last5=Beer |first5=Jürg |last6=McConnell |first6=Joseph R. |last7=Possnert |first7=Göran |last8=Sigl |first8=Michael |last9=Svensson |first9=Anders |last10=Synal |first10=Hans-Arno |last11=Welten |first11=Kees C. |last12=Woodruff |first12=Thomas E. |date=2015-10-26 |title=Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4 |journal=Nature Communications |volume=6 |pages=8611 |doi=10.1038/ncomms9611 |issn=2041-1723 |pmc=4639793 |pmid=26497389}}</ref><ref name=":2">{{Cite journal |last=Stephenson |first=F. Richard |date=2015-03-15 |title=Astronomical evidence relating to the observed 14C increases in A.D. 774–5 and 993–4 as determined from tree rings |url=https://www.sciencedirect.com/science/article/pii/S027311771400773X |journal=Advances in Space Research |language=en |volume=55 |issue=6 |pages=1537–1545 |doi=10.1016/j.asr.2014.12.014 |issn=0273-1177}}</ref>

In 2021, a scientific paper used the 993–994 carbon-14 spike as a benchmark in [[Physics:Dendrochronology|dendrochronology]] (tree-ring studies) to precisely determine that [[History:Vikings|Vikings]] were present in L'Anse aux Meadows in Newfoundland exactly 1000 years prior, in 1021 AD.<ref>{{Cite journal |last1=Kuitems |first1=Margot |last2=Wallace |first2=Birgitta L. |last3=Lindsay |first3=Charles |last4=Scifo |first4=Andrea |last5=Doeve |first5=Petra |last6=Jenkins |first6=Kevin |last7=Lindauer |first7=Susanne |last8=Erdil |first8=Pınar |last9=Ledger |first9=Paul M. |last10=Forbes |first10=Véronique |last11=Vermeeren |first11=Caroline |last12=Friedrich |first12=Ronny |last13=Dee |first13=Michael W. |date=2022-01-20 |title=Evidence for European presence in the Americas in ad 1021 |journal=Nature |language=en |volume=601 |issue=7893 |pages=388–391 |doi=10.1038/s41586-021-03972-8 |issn=0028-0836 |pmc=8770119 |pmid=34671168}}</ref>

== Historical observations ==
The solar storm hypothesis is heavily supported by several observations of aurora events from late 992 in [[Place:Korea|Korea]], {{wipe|Germany}} and Ireland, usually describing a red sky, presumably because of major auroras.<ref name=":0" /><ref name=":3" /><ref name=":2" /> The historical observations do not completely prove the cause of the 993-994 <sup>14</sup>C spike but show evidence of a strong solar event taking place late 992, as they were recorded within a relatively short time frame.<ref name=":0" /><ref name=":2" />

In the Korean Peninsula, between December 992 and January 993, a text described "heaven's gate" opening one night.<ref name=":0" /><ref name=":2" />

In the Saxony region of present-day {{wipe|Germany}} in late 992, several aurora observations were made. One set of observations, recorded October 21, 992, noted that the sky reddened three times.<ref name=":0" /> 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.<ref name=":0" />

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".<ref name=":0" />

== Similar events ==
The 993–994 carbon-14 spike was one of only a few well-documented <sup>14</sup>C events. There had been a considerably larger one, the [[Astronomy:774–775 carbon-14 spike|774-775 carbon-14 spike]], which was around 1.7 times as strong than the 993-994 event.<ref name=":1" /> Both events also had subsequent <sup>10</sup>Be spikes, which further proves that they are from strong solar activity.<ref name=":3" />

==See also==
* [[Astronomy:List of solar storms|List of solar storms]]
* [[Astronomy:774–775 carbon-14 spike|774-775 carbon-14 spike]]

==References==
{{reflist}}

{{Solar storms}}

{{DEFAULTSORT:993-994 carbon-14 spike}}
[[Category:Geomagnetic storms]]
[[Category:Dendrology]]
[[Category:Stratigraphy]]

{{Sourceattribution|993–994 carbon-14 spike}}