February 29 takes approximately 6 hours longer than 365 whole days. A leap day compensates for this lag, realigning the calendar with the Earth's position in the Solar System; otherwise, seasons would occur later than intended in the calendar year. The Julian calendar used in Christendom until the 16th century added a leap day every four years; but this rule adds too many days (roughly 3 every 400 years), making the equinoxes and solstices shift gradually to earlier dates. By the 16th century the vernal equinox had drifted to March 11, and the Gregorian calendar was introduced both to shift it back
Jewish Talmudic Calendar the previous evening, at the time of sunset, when three mediums sized stars appear. Practically it begins from 6:00 p.m. (18:00) Jerusalem time (16:00 Universal Time). A day is divided into 24 hours, each with 1080 parts (halakim). Thus each minute is composed of 18 halakim; each halakim is 3.33 seconds. There are twelve months in a common year, and thirteen months in a leap year. The New Years Day (Rosh Hashana) is Tishri 1. The months are 30 days and 29 days in turns. A regular common year is 354 days; while a regular leap year is 384 days