20 resultados para XIV-XVI centuries


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The Sun-Earth connection is studied using long-term measurements from the Sun and from the Earth. The auroral activity is shown to correlate to high accuracy with the smoothed sunspot numbers. Similarly, both geomagnetic activity and global surface temperature anomaly can be linked to cyclic changes in the solar activity. The interlinked variations in the solar magnetic activity and in the solar irradiance cause effects that can be observed both in the Earth's biosphere and in the electromagnetic environment. The long-term data sets suggest that the increase in geomagnetic activity and surface temperatures are related (at least partially) to longer-term solar variations, which probably include an increasing trend superposed with a cyclic behavior with a period of about 90 years.

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Reconsidering the initial Christian Conversion of Scotland in the fifth and sixth centuries AD, using archaeological and historical evidence, it is argued that this was carried out by missionaries from what had been Roman Britain. It is shown that this missionary activity - and similar British missions in Ireland - represents the first instance of Western missionary work beyond the former Roman imperial frontiers. The location of the northern frontier of Roman Britain in the fourth century, and the meaning of Pictish Class 1 symbol stones, are discussed as part of the broader argument.