We present a novel empirical investigation into whether the tropical zodiac should be inverted in the Southern Hemisphere. The idea of inverting astrological signs—on the basis of seasonal differences—remains a controversial topic. To examine this hypothesis, we compared astrological keyword matches from natal charts (inverted and non-inverted) with biographical profiles of 141 public figures – 68 born in the Southern Hemisphere and 73 in the Northern Hemisphere. Using the Mastro Expert System and the Semantic Proximity Evaluator, we analysed the correspondence between chart-derived keywords and approximately 150 personality traits per subject. The results show that inverted charts yield significantly better matches for Southern Hemisphere subjects (70.5%) than for Northern Hemisphere subjects (35.6%). A test for equality of proportions confirmed that this difference is highly significant, with a moderate-to-large effect size (p ≈ 1.62 × 10⁻⁵; h ≈ 0.72). These findings suggest that photoperiodism may partially influence the symbolic structure of the tropical zodiac, thereby challenging the assumption of its universality.