Spotless days landmarks

Aug 25, 2009, 4:42 AM |

The sun has now produced over 40 spotless days in a row, and that puts this minimum into really top ten terratory.


Periods with spotless days (>20 days) since 1849

Perioden met vlekkenloze dagen (>20 dagen) sinds 1849


There are coronal holes apperaing at the north and south poles of the sun and this seems to indicate that we are further along with this cycle than was thought earlier. This makes the 9th incidence of over twenty spotless days for this minimum, and this now starts to indicate an increasing liklihood of a superminimum happening.Pending further review of the preliminary daily sunspot data by SIDC, the period from 21 July 2008 till 20 August 2008 is one of the longer ones since the beginning of daily solar observations in 1849. An even longer period in recent history occured during the previous solar cycle transition, from 13 September 1996 till 24 October 1996, when the sun was spotless for 42 consecutive days. One of the longest spotless periods (since 1818) is probably from 24 October 1822 till 12 March 1823 (140 days!), but unfortunately, the series are broken on 29 December 1823 (no observation available for that day). With 8 entries so far, (and 1 happening now, that makes nine) the current solar cycle transit ranks 4th in transits with the most of 20 or more spotless days stretches. Only the transits to cycles 14 (10), 12 (12) and 15 (17) had even more such periods.