Solar ISN mean dips below 1.00

Anthony Watts
Watts Up With That
Tue, 21 Apr 2009 01:56 UTC

© SOHO

While the sun still struggles to form cycle 24 spots like seen in this weak plage area (upper right) in today's SOHO MDI and Magnetograms (shown below) Paul Stanko of NOAA writes to tell me of an interesting development in his tracking of the International Sunspot Number (ISN).



Paul writes:

My running mean of the International Sunspot Number for 2009 just dipped below 1.00. For anything comparable you now need to go back before 1913 (which scored a 1.43) which could mean we're now competing directly with the Dalton Minimum.

Just in case you'd like another tidbit, here is something that puts our 20 to 30 day spotless runs in perspective... the mother of all spotless runs (in the heart of the Maunder Minimum, of course!) was from October 15, 1661 to August 2, 1671. It totaled 3579 consecutive spotless days, all of which had obs.

Errant counting of sunspecks from Catainia aside, it appears that we haven't seen anything like this in modern history.

We live in interesting times.