A leap year is a calendar year that contains an additional day compared to a common year. The 366th day is added to keep the calendar year synchronised with the astronomical year or seasonal year. Since astronomical events and seasons do not repeat in a whole number of days, calendars having a constant number of days each year will unavoidably drift over time with respect to the event that the year is supposed to track, such as seasons. By inserting ("intercalating") an additional day—a leap day—or month—a leap month—into some years, the drift between a civilization's dating system and the physical properties of the Solar System can be corrected.
A lunisolar calendar is a calendar in many cultures, incorporating lunar calendars and solar calendars. The date of lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in the Earth's sky. If the sidereal year is used instead of the solar year, then the calendar will predict the constellation near which the full moon may occur. As with all calendars which divide the year into months there is an additional requirement that the year have a whole number of months. In some cases ordinary years consist of twelve months but every second or third year is an embolismic year, which adds a thirteenth intercalary, embolismic, or leap month.
AD 41 (XLI) was a common year starting on Sunday of the Julian calendar. At the time, it was known as the Year of the Consulship of C. Caesar Augustus Germanicus and Cn. Sentius Saturninus. The denomination AD 41 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
AD 22 (XXII) was a common year starting on Thursday of the Julian calendar. At the time, it was known as the Year of the Consulship of Agrippa and Galba. The denomination AD 22 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
AD 42 (XLII) was a common year starting on Monday of the Julian calendar. At the time it was known as the Year of the Consulship of Caesar and Largus. The denomination AD 42 for this year has been used since the Early Middle Ages, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 775 (DCCLXXV) was a common year starting on Sunday of the Julian calendar. The denomination 775 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 440 (CDXL) was a leap year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Valentinianus and Anatolius. The denomination 440 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
The 460s decade ran from January 1, 460, to December 31, 469.
Year 459 (CDLIX) was a common year starting on Thursday of the Julian calendar. At the time, it was known in the Roman Empire as the Year of the Consulship of Ricimer and Patricius. The denomination 459 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 496 (CDXCVI) was a leap year starting on Monday of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Paulus without colleague. The denomination 496 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 684 (DCLXXXIV) was a leap year starting on Friday of the Julian calendar. The denomination 684 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 719 (DCCXIX) was a common year starting on Sunday of the Julian calendar, the 719th year of the Common Era (CE) and Anno Domini (AD) designations, the 719th year of the 1st millennium, the 19th year of the 8th century, and the 10th and last year of the 710s decade. The denomination 719 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 424 (CDXXIV) was a leap year starting on Tuesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Castinus and Victor. The denomination 424 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Nisan in the Babylonian and Hebrew calendars is the month of the barley ripening and first month of spring. The name of the month is an Akkadian language borrowing, although it ultimately originates in Sumerian nisag "first fruits". In the Hebrew calendar it is the first month of the ecclesiastical year, called the "first of the months of the year", "first month", and the month of Aviv בְּחֹ֖דֶשׁ הָאָבִֽיב ḥōḏeš hāʾāḇîḇ). It is called Nissān in the Book of Esther. It is a month of 30 days. In the year 2024, 1 Nisan will occur on 9 April. Counting from 1 Tishrei, the civil new year, it would be the seventh month, but in contemporary Jewish culture, both months are viewed as the first and seventh simultaneously, and are referred to as one or the other depending on the specific religious aspects being discussed.
The Malayalam Calendar, or the Kollam Era, is a sidereal solar calendar used in Kerala. The origin of the calendar has been dated to 825 CE, commemorating the establishment of Kollam.
A calendar era is the period of time elapsed since one epoch of a calendar and, if it exists, before the next one. For example, the current year is numbered 2025 in the Gregorian calendar, which numbers its years in the Western Christian era.
Vikram Samvat, also known as the Vikrami calendar is a national Hindu calendar historically used in the Indian subcontinent and still also used in several Indian states and Nepal. It is a lunisolar calendar, using twelve to thirteen lunar months each solar sidereal years. The year count of the Vikram Samvat calendar is usually 57 years ahead of the Gregorian calendar, except during January to April, when it is ahead by 56 years.
The March equinox or northward equinox is the equinox on the Earth when the subsolar point appears to leave the Southern Hemisphere and cross the celestial equator, heading northward as seen from Earth. The March equinox is known as the vernal equinox in the Northern Hemisphere and as the autumnal equinox in the Southern Hemisphere.
A regnal year is a year of the reign of a sovereign, from the Latin regnum meaning kingdom, rule. Regnal years considered the date as an ordinal, not a cardinal number. For example, a monarch could have a first year of rule, a second year of rule, a third year of rule, and so on, but not a zeroth year of rule.
Stafford Louis Lightman is a British endocrinologist who has been Professor of Medicine, University of Bristol, since 1993. He was president of the British Neuroscience Association 2017–2019.
