This grand paper examines many lines of evidence, many well known authors, enjoy the feast
The Maunder minimum (1645–1715) was indeed a grand minimum:
A reassessment of multiple datasets
Ilya G. Usoskin, Rainer Arlt , Eleanna Asvestari, Ed Hawkins, Maarit Käpylä, Gennady A. Kovaltsov, Natalie Krivova, Michael Lockwood, Kalevi Mursula, Jezebel O’Reilly, Matthew Owens, Chris J. Scott, Dmitry D. Sokoloff, Sami K. Solanki, Willie Soon and José M. Vaquero
Astronomy & Astrophysics, accepted July 2015, 19 pages, access on registration
Aims. Although the time of the Maunder minimum (1645–1715) is widely known as a period of extremely low solar activity, it is still being debated whether solar activity during that period might have been moderate or even higher than the current solar cycle #24. We have revisited all existing evidence and datasets, both direct and indirect, to assess the level of solar activity during the Maunder minimum.
Conclusions. We conclude that solar activity was indeed at an exceptionally low level during the Maunder minimum. Although the exact level is still unclear, it was definitely lower than during the Dalton minimum of around 1800 and significantly below that of the current solar cycle #24. Claims of a moderate-to-high level of solar activity during the Maunder minimum are rejected with a high confidence level.
3.1.2. Surveys of historic aurorae
Earlier in the same solar cycle as Graham’s first geomagnetic activity observations, on the night of Tuesday Mar. 17, 1716 (Gregorian calendar: note the original paper gives the Julian date in use of the time which was Mar. 6), auroral displays were seen across much of northern Europe, famously reported by Edmund Halley (1716) in Great Britain.
What is significant about this event is that very few people in the country had ever seen an aurora before (Fara 1996). Indeed, Halley’s paper was commissioned by the Royal Society for this very reason. This event was so rare it provoked a similar review under the auspices of l’Académie des Sciences of Paris (by Giacomo Filippo Maraldi, also known as Jacques Philippe Maraldi) and generated interest at the Royal Prussian Academy of Sciences in Berlin (by Gottfried Wilhelm Leibnitz). All these reviews found evidence of prior aurorae, but none in the previous half century.
As winter approaches paper leaves are falling in Paris
Post by Tim