  This research work is based on the study of the longitudinal distribution of
the most active sunspot zones on the photosphere. Sunspot data has been
analyzed for 12 solar cycles (cycles 12-23) separately for northern and
southern hemisphere, and the entire solar sphere. The timelongitude diagrams
and their corresponding histograms have been plotted to probe the formation,
location, longitudinal spread, and lifetime of the most active sunspot
longitudes. By the analysis and comparison of the time- longitude diagrams and
histograms six active longitudes (>0, ~90, ~135, ~180, ~270 and <360 degrees)
have been identified out of which three (~90, ~180 and ~270 degrees) are
observed to be most frequent for the whole dataset analyzed. The comparison of
the northern and southern hemisphere revealed that the hemispheres do not
exhibit very similar kind of behavior. The lifetime and longitudinal spread of
sunspot active longitudes is found to be 3-5 Carrington rotations and 20-30
degrees Carrington longitude respectively. This research work also includes the
study of the movement of most active sunspot longitudes from higher to lower
latitudes in northern hemispheres for six solar cycles (cycles 18-23). For this
purpose the formation of sunspot active longitudes has been investigated in
four latitudinal belts (40-30, 30-20, 20-10 and 10-0 degrees)). It is found
that the sunspot active longitudes follow a certain longitudinal pattern during
the evolution of the 11-year solar cycle. In the beginning of a solar cycle
they seem to appear mostly around two longitudes ~0 degree and ~270 degrees in
the latitudinal belt 40-30 degrees. As the solar cycle proceeds they tend to be
stable around two longitudes ~90 degrees and ~270 degrees which are antipodal.
