Hercules A

Hercules A
Radio-Optical View of the Galaxy Hercules A - Many thanks to: NASA, ESA, S. Baum and C. O'Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA)

Sunday, January 27, 2013

No sunspots after 2017 ??

I refer to Penn and Livingston 2010:
"Long-term Evolution of Sunspot Magnetic Fields"


 From the abstract:
"...Independent of the normal solar cycle, a decrease in the sunspot magnetic field strength has been observed using the Zeeman-split 1564.8nm Fe I spectral line at the NSO Kitt Peak McMath-Pierce telescope. Corresponding changes in sunspot brightness and the strength of molecular absorption lines were also seen. This trend was seen to continue in observations of the first sunspots of the new solar Cycle 24, and extrapolating a linear fit to this trend would lead to only half the number of spots in Cycle 24 compared to Cycle 23, and imply virtually no sunspots in Cycle 25..."

13 citations to this paper at:


NOAA Space Weather Prediction Center lists ONE event on 130124 !! :


So far, the maximum monthly average sunspot number for cycle 24 occurred in November 2011: http://www.swpc.noaa.gov/SolarCycle/sunspot.gif