At 5:29 am, 16 July 1945, Mountain War Time — 9:29 pm that same evening, AEST — the Trinity test at Alamogordo, New Mexico detonated the first nuclear device on Earth. Vita Sapien counts time from that instant: the moment the species acquired the means of its own undoing, and with it, a new and permanent responsibility.
Time zero was one instant, felt at a different hour depending where you stood. Choose a time zone to see the date and hour the Vitan year turns there — for some places, it isn't even the 16th.