Astronomical year numbering
Astronomical year numbering refers to an alternative method of numbering years in relation to the
years since Christ's birth. In astronomical year numbering, the year
1 B.C. becomes 0, the year
2 B.C. becomes -1, and in general any given year
n B.C. becomes –(
n–1). Years
A.D. are identical. The system is so named due to its original use by astronomers. It is more convenient to have a year 0 when subtracting years and computing time intervals across the
epoch. However, astronomers mostly find it convenient to use Julian days when making computations.