Year zero

The year zero (0) does not exist in the Gregorian or Julian calendars. The year 1 B.C. C. immediately precedes the year 1 d. C. That is to say that after December 31 of the year 1 a. C. began on January 1 of the year 1 d. C. The same would happen with the decades, beginning the first of our Era in the year 1 d. C. and until the year 10 d. C., to thus conform the decade (ten years) which makes the year 10 d. C. is part of the first decade and not the next.

Historians adopted this convention from its use by Bede in his Historia ecclesiastica gentis Anglorum (Ecclesiastical History of the English People, dated 731). Bede did not use zero because years are counted from one and not from zero. He knew the number zero well, since zero was the first epact of the 19-year cycle used to calculate the date of Easter, as he explained in his work De temporum ratione (On the count of time, of 725). The Latin word nullae, meaning 'nothing', was used to name this epact, while the rest of the epacts were numbered with Roman numerals.

In any case, the years, like the days or the centuries, are not counted with cardinal numbers, but are ordered with ordinal numbers, among which there are no there is zero (for example, in an ordered list, before the first there is no zero position). Thus, there is no zero year in the same way that there is no zero century, nor zero day of the months, nor is there any zero day of the week. Also, the calculation of the hours was traditionally done by ordinal numbers (prime hour, secunda hour, tercia hour, etc. in Latin terminology; or twelve o'clock at night, one minute past twelve in the morning, etc. in classical Spanish terminology), until in the second half of the century XX, the generalization of numbering from digital screens and US military vocabulary, as well as the practice of timing to compare the duration of periods of time associated with popular activities such as sports, introduced into the everyday use the novel concepts of zero hour, zero minute, zero second and their submultiples.

Year zero in the proleptic Julian calendar

Astronomers introduced the year zero to standardize the chronology according to their own criteria. The calendar that uses it is called Proleptic Julian Calendar. This decision implies a gap from the previous years: the first year before Christ corresponds to the year zero, because after 12/31/1 a. C. would become directly 1/1/1 d. c.

There are two reasons for using year 0:

1. 32 B.C. to 1 B.C. is 31 years old,

   1 a.C. to 1 d.C. there is 1 year,

   1 d.C. to 15 d.C. there are 14 years.

   In total 31 + 1 + 14 = 46.

   If we interpret 32 BC as the year −31, then your age at the end of your life is calculated by taking the difference between the dates of your death and your birth: 15 − (−31) = 46.

2. It is conjecture today that Jesus of Nazareth would not have been born in the year that serves as the beginning of our calendar, but about 4 years before (between 2 BC and 7 BC according to the sources), although there is logically some controversy over the exact year (see "date of the birth of Jesus").

There are three reasons not to use year zero

1. If we changed all dates before Christ, an additional confusion would be introduced over all published historical dates.
2. If we used the numbering system with beginning 0, we should have the year 0, the century 0, the millennium 0, etc.
3. If instead of considering the 0 as a period of time, we do it as an instant (or a milestone in the time scale), from that moment on the time elapsed would start counting positively. Applying the same criterion, the time counted backward would be counted negative from the moment 0.