Summer and winter seasons caused by earth's tilting (at 23.5 degrees) of its axis joining the north and south poles.
(Summer and winter seasons; caused; by earth's tilting (at 23.5 degrees) of its axis) (Summer and winter seasons caused by earth's tilting (at 23.5 degrees) of its axis; joining; the north and south poles)
Summer and winter seasons Summer and winter seasons caused by earth's tilting (at 23.5 degrees) of its axis
caused joining
by earth's tilting (at 23.5 degrees) of its axis
the north and south poles