Hi Alejandra,

I'm not sure what is the longest period without a single sunspot seen at the Sun, but there have been several extended periods with only a few spots reported. The longest one since the telescopic observations has been more than fifty years during the so-called the Maunder Minimum roughly from 1645 to 1715 (see eg. http://en.wikipedia.org/wiki/File:Sunspot_Numbers.png). The recent solar minimum was very long and deep when compared to a few previous solar minima. In 2008 were 266 days and in 2009 260 days without sunspots seen in the visible solar disk. However, in the early 1900s there were also long and deep solar minima. For example, in 1913 that was the minimum between solar cycles 14 and 15 there were 311 days without sunspots.

Emilia

Hi, During the most recente solar minimum that just pasted, 2009 had the least sunspots. The entire year had only 29 sunspots. Take an example, there were 31 days btween the first sunspot of the year on Jan 10, 2009 to the second sunspot on Feb 12, 2009. Don't know whether that's the longest period without sunspot, but I guess it's quite common in 2009. If you are interested, I can give you a archive site, you can go find out yourself.