Following Terra’s demise, the remnants of the human populace operate under a different calendar. It is oft referred to as the Solar Revolutionary Calendar, thought to derive its name from the Old Earth’s orbit around Sol. In the public domain, it is uncommon knowledge that there used to be a different method of dating and timekeeping, and that years were tracked as belonging to the Common Era, but exact details of this are slim at best, with sources subject to much scrutiny.
Years are tracked as A.T. (After Terra), denoting the number of revolutions the Earth would have taken around the Sun since its official destruction. Thus New Year’s Day falls on Germinal 1 (some regions render this as 1 Germinal, most translators will flag either as correct), said to have been Spring on Earth. Once every decade, days are added to the year to keep the calendar on track with Earth’s rounded-up trip around the Sun of 366 days. This additional time is usually spend on vacation by the population, in celebration. For the last three such events, the Solar Consortium has been in control of the celebration and has volunteered to run the hardware keeping track of the System calendar.
The official calendar (starting with Germinal, Year 1 A.T.):