A Forecast of the Trend of Solar Activity of the Descending Branch of Cycle 21

The astronomical, astronautical and geophysical workers have common concern about the trend of sotar activity after the maximum epoch of Cycle 21. Based on a regression relation between the peak values and the length of the descending branch the terminal epoch of Cycle 21 is given, and on the similar cycles corrected with a probability function the prediction smoothed monthly means of relative numbers of the descending branch are also given.