  The existence of ~12-year and ~51-year periodicities in the north-south
asymmetry of solar activity is well known. However, the origin of these as well
as the well-known relatively short periodicities in the north-south asymmetry
is not yet clear. Here we have analyzed the combined daily data of sunspot
groups reported in Greenwich Photoheliographic Results (GPR) and Debrecen
Photoheligraphic Data (DPD) during the period 1874-2017 and the data of the
orbital positions (ecliptic longitudes) of the giant planets in ten-day
intervals during the period 1600-2099. Our analysis suggests that ~12-year and
~51-year periodicities in the north-south asymmetry of solar activity are the
manifestations of the differences in the strengths of ~11-year and ~51-year
periodicities of activity in the northern- and southern-hemispheres. During the
period 1874-2017 the Morlet wavelet power spectra of the north-south asymmetry
of sunspot-group area and the mean absolute difference of the orbital positions
of the giant planets are found to be similar. Particularly, there is a
suggestion that the ~12-year and ~51-year periodicities in the north-south
asymmetry of sunspot-group area occurred during approximately the same times as
the corresponding periodicities in the mean absolute difference of the orbital
positions of the giant planets. Therefore, we suggest that there could be
influence of some specific configurations of the giant planets in the origin of
the ~12-year and ~50-year periodicities of the north-south asymmetry of solar
activity.
