Why Saturday is Not Saturday, Nor Sunday Sunday?

This study establishes that the names of the days of the week underwent a chronological shift in history, resulting in an apparent three-day displacement relative to the ancient perspective of naming days according to the celestial body governing the first hour of nightfall. We present: 1) Archaeological evidence (Pompeii graffito dated February 6, 60 CE); 2) Babylonian-Greek-Roman astrological origins of weekday names and their order based on the ruling celestial body at dusk; 3) Coptic Easter letters by Bishop Athanasius showing two distinct naming systems for days.