The synodic month of about twenty-nine and a half days is the basis of the lunar and lunisolar calendars used across the world, and the atlas records several: the Hebrew, Islamic, Hindu and Chinese systems each solve differently the problem that twelve lunar months fall about eleven days short of the solar year. The Islamic calendar simply lets the year drift; the Hebrew and Chinese insert intercalary months; the Hindu system does both in different regional forms. Lunar deities are as widespread as solar ones and are as often male as female, which is worth stating because the modern popular association of the Moon with the feminine is a generalisation that the historical record does not support: Sin and Nanna in Mesopotamia, Thoth and Khonsu in Egypt, Chandra and Soma in India, and Tsukuyomi in Japan are all male, while Selene, Luna, Artemis-Diana and Chang-e are female.
Two different months lie behind those calendars and confusing them is the commonest error in reading a lunar date. The synodic month, 29.53 days, is phase to phase, new moon to new moon, and it is what a lunar calendar counts. The sidereal month, 27.32 days, is the Moon's return to the same star, and it is what a nakshatra or mansion scheme counts. The difference of just over two days is the Sun's own movement during the month, which the Moon has to make up. The eleven day shortfall against the solar year resolves neatly at nineteen years: 235 synodic months come to within about two hours of 19 tropical years, the Metonic cycle, and it is that near coincidence the Hebrew and Chinese intercalation schemes exploit.