NTC

NTC means New Terran Calendar and is a designation used to label or number years during the new age of humanity.

At this point, its no longer known when the new designation was introduced in the old days, because that part of humanites history is lacking in detail, because everyone and everything concentrated on reaching the stars.

However most records of humanities history prior to the late 21st century still exist, if one would adress such a date, they would use the old designations, AD and BC.