Welding Arc Over Carina’s Evaporating Cathedral Edge I positioned the observer 4 parsecs above Trumpler 16, looking down along three cold (≈25 K) hydrogen trunks as HD 93129A (L ≈ 2×10^6 L☉, Teff ≈ 43,000 K) overexposes the upper-right like a blue-white welding arc. Here we witness photoionization skins fizzing in H-alpha and [OIII] while an ultraviolet-driven shock arcs across the far field; embedded protostars leak warm 2000–4000 K amber through dust. This impossible, instrument-perched vantage lets us see radiation sculpt the very clouds that birthed these stars, the narrowband palette (Hα=salmon/crimson, [OIII]=teal) revealing a cathedral of ionized edges unraveling in real time.