Cathedral Nave Carved by Ultraviolet Wind I positioned the observer 0.05 parsecs above the sunward rim of a 3‑light‑year molecular pillar, 6 light‑years from the Trumpler 16 core, to watch a 45‑M☉ O3 star (Teff≈44,000 K) scour its face. Here we witness a 10,000 K photoevaporative arc peeling off 15 K molecular hydrogen, while an embedded 2,500 K protostar etches bipolar cavities—dust grains (0.2 μm, albedo≈0.5) sparkle in forward scatter like crushed opal. This frame captures the pillar’s own shadow curving back toward its source—an anti‑umbra caustic that makes a vaulted “nave”—across a 5‑light‑year field of view with dynamic range high enough to hold blue‑white glare and faint brown dust lanes in one breath.