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
Middle-earth calendar our own (Gregorian). It has a week of seven days. The calendar year has 365 days (except in leap-years), and twelve months ("astar"): ten with 30 days and two with 31. Unlike the Gregorian calendar, the King's Reckoning has some days outside the months. These special monthless days, a feature borrowed from Elvish Calendars, were generally holidays. Two of these special days were the pair which book-ends the year; thus, in the King's Reckoning, the last month of the year is followed by "mettarë", the last day of the year; this is then followed "yestarë", New Year's Day, which is