Another approach to estimating the year of birth is based on an attempt to work backwards from the point when Jesus began preaching, using the statement in Luke 3:23 that he was "about 30 years of age" at that time.[25] Jesus began to preach after being baptized by John the Baptist, and based on Luke's gospel John only began baptizing people in "the fifteenth year of the reign of Tiberius Caesar" (Luke 3:1–2), which scholars estimate would place the year at about AD 28–29.[25][26][27][28][29] By working backwards from this, it would appear that Jesus was probably born no later than 1 BC.[6][25][28] Another theory is that Herod's death was as late as after the January eclipse of 1 BC[30] or even AD 1[31] after the eclipse that occurred in December 1 BC.[32]