x1 is Summer(time)/(a)estival [hot season] in the northern hemisphere and Winter(time)/hibernal/hiemal [cold season] in the southern hemisphere of year x2 and for celestial body x3.
x1 is Spring time/vernal [warming season] in the southern hemisphere and Autumn/autumnal [cooling season] in the northern hemisphere of year x2 and for celestial body x3.
x1 is Summer(time)/(a)estival [hot season] in the southern hemisphere and Winter(time)/hibernal/hiemal [cold season] in the northern hemisphere of year x2 and for celestial body x3.
x1 is Spring time/vernal [warming season] in the northern hemisphere and Autumn/autumnal [cooling season] in the southern hemisphere of year x2 and for celestial body x3.