Sequences of Spotless Days on the Sun
During solar minimum it is not unusual to see consecutive numbers of days where there no sunspots observed on the visible solar disc.
The table below compares observations since 1850.
|Year of Sequence||Number of Consecutve Spotless Days|
|1900, 1912, 1933-34, 2008||31|
The table shows that the later solar minima, are still considerably shorter than some in the 19th and early 20th century in terms of consecutive spotless days. However, a note of caution is required because the coverage of observations was not nearly as good then as it is now. A sequence of spotless days can be broken by a single day on which a small spot appears. Lack of coverage by observations could therefore be very important in determining the length of such spotless sequences.
With the above qualification, the sequence in 1996 is still the longest observed in recent times during which good observations have been available.
Around solar maximum there will normally be few or no years where the visible disc of the Sun is spotless. The table below shows the total number of spotless days around each minima year. Again, use caution when considering the early data.
|Year of Minimum||Total Number of Spotless Days Around Minimum|
It is interesting that there is a general trend for the number of spotless days to decrease when solar maximums are larger. With the increasing spotless days count, could we be heading towards a period of lower solar maxima?