Microscopic pigment granules produced by skin pigment cells aggregate around the cell's nucleus to shield the DNA from the marauding rays and prevent mutation. It is irrelevant whether the ultraviolet radiation came from a bulb or a star.
人工晒黑业承诺：机器射出的紫外线比太阳的自然辐射伤害要小。但无论哪种情况，晒黑都是人体受伤的反应。皮肤色素细胞产生的微小色素颗粒聚集在细胞核旁，保护DNA免受紫外线侵袭，防止细胞发生变异。究竟紫外线是来自灯泡还是某个星体，这并不重要。