Coordinated Universal Time
The difference UT ‑ UTC between Universal Time UT and Coordinated Universal Time UTC fluctuates between -1 and 1 seconds. Hence, their absolute difference |UT ‑ UTC| never exceeds 1 second.
The beginning of our era is the point in time which is denoted by [1‑1‑1; 00:00:00]. Therefore, the first turn of year was [1‑1‑2; 00:00:00], because this is the point in time one second after [31‑12‑1; 23:59:59]. Therefore, the first turn of decade was [1‑1‑11; 00:00:00], because this is the point in time one second after [31‑12‑10; 23:59:59]. Analogously, the first turn of century was [1‑1‑101; 00:00:00]. Analogously, the first turn of millenium was [1‑1‑1001; 00:00:00]. Analogously, the second turn of millenium was [1‑1‑2001; 00:00:00]. As a consequence, the first day of the third millennium was 1‑1‑2001 and its first year 2001 (not year 2000).
Our era is the Christian era, but nobody knows precisely when Jesus was born. Nevertheless, in AD 525, more than five centuries after Jesus’ birth, the first year 1 of the Christian era was exactly and definitively laid down by the learned Scythian monk Dionysius Exiguus (see section ‘The classical Alexandrian 19-year lunar cycle’ p. 67-70). Therefore, most Christians believe that He was born either on 25-12-1 or on the day just a week before 1-1-1. As a matter of fact, Charlemagne must have believed that Jesus was born exactly a week before 1-1-1, because he let himself crown emperor on 25‑12-800. However, according to modern historians, Jesus was born some years before the beginning of the Christian era and died at 3-4-33.
Keep in mind that in the framework of our era Thursday 4‑10‑1582 was the very last calendar day of the (proleptic) Julian calendar, and that that Thursday was immediately followed by Friday 15‑10‑1582 being the very first calendar day of the Gregorian calendar. As a matter of fact, the year 1582 had only 355 days. Thus that year is the only calendar year of our era which had a number of days which is not 365 (which is the number of days of any normal calendar year) or 366 (which is the number of days of any leap year). Between the first year (AD 1) and the present year (2020) of our era there were only four calendar years of our era whose year number was divisible by 4 but whose number of days was nevertheless 365, namely the fourth year (AD 4) of our era and the years 1700, 1800, and 1900. This implies that 1-1-1 was a Sunday, which simple fact can easily be derived from Annianus’ 532-year Paschal cycle being part of Beda Venerabilis’ Easter table (see Appendix II p. 106-120).
© Jan Zuidhoek 2019-2020