January is the first month of the year in the Julian and Gregorian calendars and the first of seven months to have a length of 31 days. The first day of the month is known as New Year's Day. It is, on average, the coldest month of the year within most of the Northern Hemisphere and the warmest month of the year within most of the Southern Hemisphere. In the Southern hemisphere, January is the seasonal equivalent of July in the Northern hemisphere and vice versa.
February is the second and shortest month of the year in the Julian and Gregorian calendar with 28 days in common years and 29 days in leap years, with the quadrennial 29th day being called the leap day. It is the first of five months to have a length of fewer than 31 days, and the only month to have a length of fewer than 30 days, with the other seven months having 31 days. In 2019, February had 28 days.
March is the third month of the year and named after Mars in both the Julian and Gregorian calendars. It is the second of seven months to have a length of 31 days. In the Northern Hemisphere, the meteorological beginning of spring occurs on the first day of March. The March equinox on the 20 or 21 marks the astronomical beginning of spring in the Northern Hemisphere and the beginning of autumn in the Southern Hemisphere, where September is the seasonal equivalent of the Northern Hemisphere's March.
September is the ninth month of the year in the Julian and Gregorian calendars, the third of four months to have a length of 30 days, and the fourth of five months to have a length of less than 31 days. In the Northern Hemisphere September is the seasonal equivalent of March in the Southern Hemisphere.
The Julian calendar, proposed by Julius Caesar in 46 BC, was a reform of the Roman calendar. It took effect on 1 January 45 BC, by edict. It was the predominant calendar in the Roman world, most of Europe, and in European settlements in the Americas and elsewhere, until it was refined and gradually replaced by the Gregorian calendar, promulgated in 1582 by Pope Gregory XIII.
The Gregorian calendar is the calendar used in most of the world. It is named after Pope Gregory XIII, who introduced it in October 1582. The calendar spaces leap years to make the average year 365.2425 days long, approximating the 365.2422-day tropical year that is determined by the Earth's revolution around the Sun. The rule for leap years is:
Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the year 2000 is.
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North Pole.
In the Northern hemisphere, the beginning of the meteorological autumn is on 1 September. In the Southern hemisphere, the beginning of the meteorological spring is on 1 September.
Autumn, also known as fall in American English and sometimes in Canadian English, is one of the four temperate seasons. Autumn marks the transition from summer to winter, in September or March, when the duration of daylight becomes noticeably shorter and the temperature cools considerably. One of its main features in temperate climates is the shedding of leaves from deciduous trees.
Spring is one of the four temperate seasons, following winter and preceding summer. There are various technical definitions of spring, but local usage of the term varies according to local climate, cultures and customs. When it is spring in the Northern Hemisphere, it is autumn in the Southern Hemisphere and vice versa. At the spring equinox, days and nights are approximately twelve hours long, with day length increasing and night length decreasing as the season progresses.
September marks the beginning of the ecclesiastical year in the Eastern Orthodox Church. It is the start of the academic year in many countries, in which children go back to school after the summer break, sometimes on the first day of the month.
The Eastern Orthodox Liturgical Calendar describes and dictates the rhythm of the life of the Eastern Orthodox Church. Passages of Holy Scripture, saints and events for commemoration are associated with each date, as are many times special rules for fasting or feasting that correspond to the day of the week or time of year in relationship to the major feast days.
The Eastern Orthodox Church, officially the Orthodox Catholic Church, is the second-largest Christian church, with approximately 200–260 million members. It operates as a communion of autocephalous churches, each governed by its bishops in local synods, although roughly half of Eastern Orthodox Christians live in Russia. The church has no central doctrinal or governmental authority analogous to the Bishop of Rome, but the Ecumenical Patriarch of Constantinople is recognised by all as primus inter pares of the bishops. As one of the oldest religious institutions in the world, the Eastern Orthodox Church has played a prominent role in the history and culture of Eastern and Southeastern Europe, the Caucasus, and the Near East.
An academic term is a portion of an academic year, the time during which an educational institution holds classes. The schedules adopted vary widely.
September (from Latin septem, "seven") was originally the seventh of ten months on the oldest known Roman calendar, with March (Latin Martius ) the first month of the year until perhaps as late as 153 BC.After the calendar reform that added January and February to the beginning of the year, September became the ninth month, but retained its name. It had 29 days until the Julian reform, which added a day.
September or mensis September was originally the seventh of ten months on the ancient Roman calendar that began with March. It had 29 days. After the reforms that resulted in a 12-month year, September became the ninth month, but retained its name. September followed what was originally Sextilis, the "sixth" month, renamed Augustus in honor of the first Roman emperor, and preceded October, the "eighth" month that like September retained its numerical name contrary to its position on the calendar. A day was added to September in the mid-40s BC as part of the Julian calendar reform.
The Roman calendar was the calendar used by the Roman kingdom and republic. The term often includes the Julian calendar established by the reforms of the dictator Julius Caesar and emperor Augustus in the late 1st century BC and sometimes includes any system dated by inclusive counting towards months' kalends, nones, and ides in the Roman manner. The term usually excludes the Alexandrian calendar of Roman Egypt, which continued the unique months of that land's former calendar; the Byzantine calendar of the later Roman Empire, which usually dated the Roman months in the simple count of the ancient Greek calendars; and the Gregorian calendar, which refined the Julian system to bring it into still closer alignment with the solar year and is the basis of the current international standard.
Martius or mensis Martius ("March") was the first month of the ancient Roman year until possibly as late as 153 BC. After that time, it was the third month, following Februarius (February) and preceding Aprilis (April). Martius was one of the few Roman months named for a deity, Mars, who was regarded as an ancestor of the Roman people through his sons Romulus and Remus.
Ancient Roman observances for September include Ludi Romani, originally celebrated from September 12 to September 14, later extended to September 5 to September 19. In the 1st century BC, an extra day was added in honor of the deified Julius Caesar on 4 September. Epulum Jovis was held on September 13. Ludi Triumphales was held from September 18–22. The Septimontium was celebrated in September, and on December 11 on later calendars. These dates do not correspond to the modern Gregorian calendar. In 1752, the British Empire adopted the Gregorian calendar. In the British Empire that year, September 2 was immediately followed by September 14.
The Ludi Romani was a religious festival in ancient Rome. Usually including multiple ceremonies called ludi. They were held annually starting in 366 BC from September 12 to September 14, later extended to September 5 to September 19. In the last 1st century BC, an extra day was added in honor of the deified Julius Caesar on 4 September. The festival first introduced drama to Rome based on Greek drama.
In ancient Roman religion, the Epulum Jovis was a sumptuous ritual feast offered to Jove on the Ides of September and a smaller feast on the Ides of November. It was celebrated during the Ludi Romani and the Ludi Plebeii.
In the Roman Empire of the 4th century, the Ludi Triumphales were games (ludi) held annually September 18–22 to commemorate the victory of Constantine over Licinius at Chalcedon in 324. No description of these games has survived, but they are significant in the historical transformation of Roman religious and state institutions under the Christian emperors, an era inaugurated by the conversion of Constantine. Forty-eight circus races (ludi circenses) are recorded for September 18, which was also celebrated as the birthday (dies natalis) of the emperor Trajan.
September was called "harvest month" in Charlemagne's calendar.September corresponds partly to the Fructidor and partly to the Vendémiaire of the first French republic. On Usenet, it is said that September 1993 (Eternal September) never ended. September is called Herbstmonat, harvest month, in Switzerland. The Anglo-Saxons called the month Gerstmonath, barley month, that crop being then usually harvested.
Meteor showers that occur in September include the Aurigids, the Delta Aurigids which occur from mid-September to early October, the Southern Taurids, which occur from September 10 to November 20, and the Andromedids which occur from September 25 – December 25.
The September equinox takes place in this month, and certain observances are organized around it. It is the Autumn equinox in the Northern Hemisphere, and the Vernal Equinox in the Southern Hemisphere. The dates can vary from 21 September to 24 September (in UTC).
September is mostly in the sixth month of the astrological calendar (and the first part of the seventh), which begins at the end of March/Mars/Aries.
This list does not necessarily imply either official status or general observance.
(Please note that all Baha'i, Islamic, and Jewish observances begin at sundown prior to the date listed, and end at sundown of the date in question unless otherwise noted.)
April is the fourth month of the year in the Gregorian calendar, the fifth in the early Julian, the first of four months to have a length of 30 days, and the second of five months to have a length of less than 31 days.
August is the eighth month of the year in the Julian and Gregorian calendars, and the fifth of seven months to have a length of 31 days. It was originally named Sextilis in Latin because it was the sixth month in the original ten-month Roman calendar under Romulus in 753 BC, and March was the first month of the year. About 700 BC, it became the eighth month when January and February were added to the year before March by King Numa Pompilius, who also gave it 29 days. Julius Caesar added two days when he created the Julian calendar in 46 BC, giving it its modern length of 31 days. In 8 BC, it was renamed in honor of Augustus. According to a Senatus consultum quoted by Macrobius, he chose this month because it was the time of several of his great triumphs, including the conquest of Egypt.
December is the twelfth and final month of the year in the Julian and Gregorian Calendars and is the seventh and last of seven months to have a length of 31 days.
June is the sixth month of the year in the Julian and Gregorian calendars, the second of four months to have a length of 30 days, and the third of five months to have a length of less than 31 days. June contains the summer solstice in the Northern Hemisphere, the day with the most daylight hours, and the winter solstice in the Southern Hemisphere, the day with the fewest daylight hours. June in the Northern Hemisphere is the seasonal equivalent to December in the Southern Hemisphere and vice versa. In the Northern Hemisphere, the beginning of the traditional astronomical summer is 21 June. In the Southern Hemisphere, meteorological winter begins on 1 June.
July is the seventh month of the year in the Julian and Gregorian Calendars and the fourth of seven months to have a length of 31 days. It was named by the Roman Senate in honour of Roman general Julius Caesar, it being the month of his birth. Prior to that, it was called Quintilis, being the fifth month of the 10-month calendar.
May is the fifth month of the year in the Julian and Gregorian Calendars and the third of seven months to have a length of 31 days.
November is the eleventh and penultimate month of the year in the Julian and Gregorian Calendars, the fourth and last of four months to have a length of 30 days and the fifth and last of five months to have a length of less than 31 days. November was the ninth month of the ancient Roman calendar. November retained its name when January and February were added to the Roman calendar. November is a month of late spring in the Southern Hemisphere and late autumn in the Northern Hemisphere. Therefore, November in the Southern Hemisphere is the seasonal equivalent of May in the Northern Hemisphere and vice versa. In Ancient Rome, Ludi Plebeii was held from November 4–17, Epulum Jovis was held on November 13 and Brumalia celebrations began on November 24. These dates do not correspond to the modern Gregorian calendar.
New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.
October is the tenth month of the year in the Julian and Gregorian Calendars and the sixth of seven months to have a length of 31 days. The eighth month in the old Roman calendar, October retained its name after January and February were inserted into the calendar that had originally been created by the Romans. In Ancient Rome, one of three Mundus patet would take place on October 5, Meditrinalia October 11, Augustalia on October 12, October Horse on October 15, and Armilustrium on October 19. These dates do not correspond to the modern Gregorian calendar. Among the Anglo-Saxons, it was known as Ƿinterfylleþ, because at this full moon (fylleþ) winter was supposed to begin.
The Revised Julian calendar, also known as the Milanković calendar, or, less formally, new calendar, is a calendar proposed by the Serbian scientist Milutin Milanković in 1923, which effectively discontinued the 340 years of divergence between the naming of dates sanctioned by those Eastern Orthodox churches adopting it and the Gregorian calendar that has come to predominate worldwide. This calendar was intended to replace the ecclesiastical calendar based on the Julian calendar hitherto in use by all of the Eastern Orthodox Church. The Revised Julian calendar temporarily aligns its dates with the Gregorian calendar proclaimed in 1582 by Pope Gregory XIII for adoption by the Christian world. The calendar has been adopted by the Orthodox churches of Constantinople, Albania, Alexandria, Antioch, Bulgaria, Cyprus, Greece, Poland, and Romania.
The Coptic calendar, also called the Alexandrian calendar, is a liturgical calendar used by the Coptic Orthodox Church and also used by the farming populace in Egypt. This calendar is based on the ancient Egyptian calendar. To avoid the calendar creep of the latter, a reform of the ancient Egyptian calendar was introduced at the time of Ptolemy III which consisted of the intercalation of a sixth epagomenal day every fourth year. However, this reform was opposed by the Egyptian priests, and the reform was not adopted until 25 BC, when the Roman Emperor Augustus imposed the Decree upon Egypt as its official calendar. To distinguish it from the Ancient Egyptian calendar, which remained in use by some astronomers until medieval times, this reformed calendar is known as the Coptic calendar. Its years and months coincide with those of the Ethiopian calendar but have different numbers and names.
Adherents of Zoroastrianism use three distinct versions of traditional calendars for liturgical purposes, all derived from medieval Iranian calendars, ultimately based on the Babylonian calendar as used in the Achaemenid empire. "Qadimi" ("ancient") is a traditional reckoning introduced in 1006. "Shahanshahi" ("imperial") is a calendar reconstructed from the 10th-century text Denkard. "Fasli" is a term for a 1906 adaptation of the 11th-century Jalali calendar, following a proposal by Kharshedji Rustomji Cama made in the 1860s.
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.
Lists of holidays by various categorization.
The adoption of the Gregorian Calendar was an event in the modern history of most nations and societies, marking a change from their traditional dating system to the modern dating system that is widely used around the world today. Some countries adopted the new calendar from 1582, some did not do so before the early twentieth century, and others did so at various dates between; however a number continue to use a different civil calendar. For many the new style calendar is only used for civil purposes and the old style calendar remains used in religious contexts. Today, the Gregorian calendar is the world's most widely used civil calendar. During – and for some time after – the change between systems, it has been common to use the terms Old Style and New Style when giving dates, to indicate which calendar was used to reckon them.