Sun
From chi and h
The diagram shows the sunspot number for the years around 2008/2009. The horizontal axis is a day counter known as the Julian Date (here minus 2,450,000 days). The sunspot counts on the vertical axis are calculated as the total number of spots plus ten times the number of sunspot groups. The red curve shows the International Sunspot Data, which are the continuation of the Zürich sunspot numbers, which go back to the middle of the 19th century. The green curve shows my own counts, which have been reported to the British Astronomical Association, and the blue curve shows the collated data from all BAA observers. For all three curves the daily spot counts have been averaged first over 30 days and then over 9 such 30-day periods. The sunspot number goes up and down in cycles of about 11 years length. The current minimum came somewhat late and lasted rather long, raising worries of very few sunspots for decades to come. In late 2009 is seems possible to say, however, that the minimum is over and that increasing sunspot numbers can be expected for the next few years.
 Sun 2002-11-10. |
 Rotation of the Sun 2006-08. |
 Annular solar eclipse 2005-10-03. |
 Total solar eclipse 2006-03-29. |
