出典:Wiktionary
出典:『Wiktionary』 (2024/12/20 12:41 UTC 版)
出典:Wikipedia
出典:『Wikipedia』 (2011/06/23 04:22 UTC 版)
Generally speaking, a calendar year begins on the New Year's Day of the given calendar system and ends on the day before the following New Year's Day. By convention, a calendar year consists of a natural number of days. To reconcile the calendar year with an astronomical cycle (which could not possibly be reckoned in a whole number of days), certain years contain extra days. Through further insertion of non-day units of time, the calendar year can be further synchronized; however, these extra units of time are not considered part of the calendar.