The Sun Recorded Through History

The Sun is nowadays observed using di? erent techniques that provide an almost instantaneous 3-D map of its structure. Of particular interest is the studyofthevariabilityinthesolaroutputproducedbythedissipationofm- netic energy on di? erent spatial and temporal scales – the so-called magnetic activity. The 11-year cycle is the main feature describing this phenomenon. Apart from its intrinsic scienti? c interest, this topic is worth studying because of the interaction of such processes with the terrestrial environment. A ? eet of space and ground-based observatories are currently monitoring the behaviour of our star on a daily basis. However, solar activity varies not only on this decadal time-scale, as has been attested mainly through two methods: (a) records of the number of sunspots observed on the solar surface from 1610, and (b) the records of 14 10 cosmogenic isotopes, such as Cand Be, measured in tree-rings and i- cores, respectively. The study of the long-term behaviour of solar activity may be comp- mented by the study of historical accounts describing phenomena directly or indirectly related to solar activity. Numerous scienti? c and non-scienti? c d- uments have reported these events and we can make use of them as a proxy of solar activity in past times.