[[Mikaye eventsevent]]s, such as the ones in [[774–775 carbon-14 spike|774-775]] and [[993–994 carbon-14 spike|993-994]], can provide fixed reference points in an unknown time sequence as they are due to cosmic radiation. As they appear as spikes in [[carbon 14]] in tree rings for that year all round the world, they can be used to date historical events to the year.<ref>{{Cite web |last=Price |first=Michael |date=13 April 2023 |title=Marking time: Radiocarbon timestamps left in ancient tree rings by cosmic ray bombardments can date historical events with unprecedented precision |url=https://www.science.org/content/article/marking-time-cosmic-ray-storms-can-pin-precise-dates-history-ancient-egypt-vikings|website=[[Science (journal)|Science]] |quote=A previous version "Marking time: Cosmic ray storms can pin precise dates on history from ancient Egypt to the Vikings" appeared in Science, Vol 380, Issue 6641.}}</ref> For example, wooden houses in the [[Viking]] site at [[L'Anse aux Meadows]] in Newfoundland were dated by finding the layer with the 993 spike, which showed that the wood is from a tree felled in 1021.<ref>{{cite journal|url=https://www.nature.com/articles/s41586-021-03972-8.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.nature.com/articles/s41586-021-03972-8.pdf |archive-date=2022-10-09 |url-status=live|journal=Nature|title=Evidence for European presence in the Americas in AD 1021|first=Margot|last= Kuitems|display-authors=etal|date=20 October 2021|volume=601|issue=7893|pages=388–391|doi=10.1038/s41586-021-03972-8|pmid=34671168|pmc=8770119|s2cid=239051036}}</ref>
