Cruising the solar cycle minimum

According to the preliminary sunspot numbers from SILSO, the Sun has been spotless from 22 October till 8 November. This period of 18 days is the longest spotless stretch so far this solar cycle transit. It's still much lower than the 32 days during the previous solar cycle transit, when the Sun was immaculate from 31 July till 31 August 2009 (See the "Spotless Days" page and this STCE Newsitem.

The end of the spotless stretch came from a small spot that appeared in the northern hemisphere. It had a latitude of +26 degrees and the correct magnetic polarity of the new solar cycle (SC25). Unfortunately, it didn't receive a NOAA number, making it similar to some other, much tinier, groups earlier this year (see here for a similar case). From late on 11 November onwards, there was a somewhat larger sunspot region at latitude +6 degrees near the disk centre. NOAA 2726 belonged to the old solar cycle (SC24), as can be seen from its magnetic polarity which is opposite to that of the unnumbered group. The images underneath were created with JHelioviewer from SDO/HMI pictures.




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