660s BC

This article concerns the period 669 BC – 660 BC.

Millennium: 1st millennium BC


At a slightly uncertain date in the latter part of this decade, there was an extreme solar particle event comparable with the event detected at AD 774/775[1] The exact date, and duration of the event is unclear due in part to an approximate 2-year residence time of the nuclei generated in the atmosphere, before they "rained out" to be incorporated into tree rings and glacial ice, but the event seems to have happened in the latter part of this decade. The possibility of there being a series of events spread over a period of time remains in consideration. What meteorological and astronomical phenomena would have accompanied this event remains an open question. The estimated "brightness" of the event is about 2 orders of magnitude stronger than any that has been instrumentally recorded since the dawn of the Space Age.


  1. ^ Paschal O'Hare (2019). "Multiradionuclide evidence for an extreme solar proton event around 2,610 B.P. (∼660 BC)". Proceedings of the National Academy of Sciences. 116 (13): 5961–5966. Bibcode:2019PNAS..116.5961O. doi:10.1073/pnas.1815725116. PMC 6442557. PMID 30858311.