 The Long Count's "zero date" was set at a point in the past marking the end of the third world and the beginning of the current one, which corresponds to 11 August 3114 BC in the proleptic Gregorian calendar.This means that the fourth world reached the end of its 13th bʼakʼtun, or Maya date 13.0.0.0.0, on 21 December 2012.In 1957, Mayanist and astronomer Maud Worcester Makemson wrote that "the completion of a Great Period of 13 bʼakʼtuns would have been of the utmost significance to the Maya."