Solar maximum

In 2006, NASA initially expected a solar maximum in 2010 or 2011, and thought that it could be the strongest since 1958.

[4] However, the solar maximum was not declared to have occurred until 2014, and even then was ranked among the weakest on record.

Some researchers suggest that grand solar maxima have shown some correlation with global and regional climate changes, although others dispute this hypothesis (e.g., see Medieval Warm Period).

Following the advent of telescopic solar observation with Galileo's 1611 observations, the intensity of solar maxima is typically measured by counting numbers and size of sunspots; for periods previous to this, isotope ratios in ice cores can be used to estimate solar activity.

The table below shows the approximate dates of some of the proposed solar minima in historical times.

A prediction for Sunspot Cycle 24 (2008-2020) gives a smoothed sunspot number maximum of about 66 in the Summer of 2013. Current observations make this the smallest sunspot cycle since records began in the 1750s. [ 1 ]
Three recent solar cycles
400 year history of sunspot numbers .