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The solar activity cycle entered a prolonged quiet phase that started in 2008 and ended in 2010. This minimum lasted for a year longer than expected and all activity proxies, as measured from Earth and from Space, reached minimum values never observed before (de Toma, 2012). The number of spotless days from 2006 to 2009 totals 800, the largest ever recorded in modern times. Solar irradiance was at historic minimums. The interplanetary magnetic field was measured at values as low as 2.9 nT and the cosmic rays were observed at records-high. While rumors spread that the Sun could be entering a grand minimum quiet phase (such as the Maunder minimum of the XVII century), activity took over in 2010 and we are now well into Solar Cycle 24 (albeit, probably, a low intensity cycle), approaching towards a maximum due by mid 2013. In addition to bringing us the possibility to observe a quiet state of the Sun and of the Heliosphere that was previously not recorded with modern instruments, the Sun has also shown us how little we know about the dynamo mechanism that drives its activity as all solar cycle predictions failed to see this extended minimum coming.

Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 7 , Transactions T28A: Transactions IAU , December 2011 , pp. 61 - 68
Copyright
Copyright © International Astronomical Union 2012

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