Calendar

A cyclical system of measuring the passage of time. The day is the fundamental unit of computation in any calendar. Most ancient civilizations (and perhaps some non-literate prehistoric societies) developed calendrical systems to mark the passage of time and various methods have been employed by different peoples. Where these were both carefully calculated and written down, as in Egypt, Mesopotamia and Mesoamerica, they are of considerable assistance to archaeologists for dating purposes. In the Americas, the origins of calendrics are still obscure, but evidence from Monte Albán suggests that the 52-year Calendar Round was known by the 6th century BC. The Long Count system was in use by c 1st century BC if not before. Ancient Near Eastern calendars varied from city to city and from period to period. In most cities the year started in the spring and was divided into 12 or 13 months. In some places the months were of fixed length; in others they were lunar months starting at the first sighting of the crescent of the new moon. As there are more than 12 lunar months in a solar year additional, or intercalary, months were included so that every third year contained 13 months. The earliest Egyptian calendars were based on lunar observations combined with the annual cycle of the Nile inundation, measured with nilometers. On this basis, the Egyptians divided the year into 12 months and three seasons: akhet (inundation), peret (spring/ crops), and shemu (harvest). The Egyptians had 30-day months and 5 intercalary days in their solar or civil calendar. For agricultural purposes and for determining religious festivals, they used a different calendar based on observations of Sirius, the dog star. The calendar in use in ancient Mesopotamia and the Levant was lunar, based on 12 months of 30 days each. This produced a year of only 354 days, about 11-1/4 days short of the true solar year; the necessary correction was made by the addition of seven months over a period of 19 years. This type of calendar is still used in both Judaism and Islam for religious purposes, though many countries now also employ the Gregorian solar calendar for secular purposes. The origin of the calendric system in general use today - the Gregorian calendar - can be traced back to the Roman republican calendar, which is thought to have been introduced by the fifth king of Rome, Tarquinius Priscus (616-579 BC). This calendar was likely derived from an earlier Roman calendar - a lunar system of 10 months - that was supposedly devised about 738 BC by Romulus, the founder of Rome. In the year 46 BC, Julius Caesar corrected the calendar by having a year of 445 days (known as the ultimus annus confusionis' or 'the last year of the muddled reckoning'). He then adapted the Egyptian solar calendar for Roman use, inserting extra days in the shorter months to bring the total up to 365, with the addition of a single day between the 23rd and 24th February in leap years. This calendar, known as the Julian Calendar, remained in use until the time of Gregory XIII in 1582, who made a further correction (of eleven days) and instituted the calendar which is in general use today. Very useful to Mesoamerican archaeologists is the Maya Long Count or Initial Series, which was a means of recording absolute time. Its starting date of 3113 BC (using the Goodman-Thompson-Martinex correlation) marks some mythical event in Maya history and itself stands at the beginning of a cycle 13 Baktuns long. A Baktun at 144,000 days in the largest unit of time in the calendar and is further divided into smaller units: the Katun (7200 days); the Tun (360 days); the Uninal (20 days) and the Kin (a single days). Thus Long Count dates are expressed in terms of these units in a five place notation. Therefore the date 9.18.0.0.0. indicates the passage of 9 x 144,000 plus 18 x 7200 days since the initial date of 3113 BC. In cultural contexts, however, the dates are inscribed as a series of hieroglyphs which incorporate numeration via bars (units of five) and dots (units of one). Short count dating replaced the Long Count after 900 AD and the Katun replaced the Baktun as the largest unit. It is less precise, however.

Most ancient civilizations (and perhaps some non-literate prehistoric societies) developed calendrical systems to mark the passage of time. Where these were both carefully calculated and written down, as in Egypt, Mesopotamia and Mesoamerica, they are of considerable assistance to archaeologists for dating purposes. The Egyptians employed a solar calendar of 355 days in a year (divided into 12 months of 3G days plus 5 intercalary days) for civil purposes. This civil calendar naturally diverged from the real solar year (which has 365.2422 days) by increasing amounts. For agricultural purposes and for determining the dates of religious festivals they used a different calendar based on observations of the dog star Sirius, known to them as Sothis, whose annual heliacal rising (i.e. rising at the same time as the sun) conveniently preceded the Nile Flood. The two calendars would coincide every 1,460 years (known as the Sothic cycle). The fortunate survival of three texts which record the date in the civil year on which Sirius rose heliacally on three different occasions (probably in 1469, 1537 and 1872 bc) has assisted in the reconstruction of ancient Egyptian chronology. The calendar in use in ancient Mesopotamia and the Levant was lunar, based on twelve months of 30 days each. This produced a year of only 354 days, about 11 "/4 days short of the true solar year; the necessary correction was made by the addition of seven months over a period of 19 years. This type of calendar is still used in both Judaism and Islam for religious purposes, though many countries now also employ the Gregorian solar calendar for secular purposes. Among the Greeks almost every community had a calendar of its own, but all were lunar calendars. Some of the Greek month names occur in Linear B, indicating that a calendar of this type was already in use in Mycenaean times. Ordinary years in Greek calendars consisted of 12 months of 29 or 30 days; leap years of 13 months were inserted from time to time (but not apparently according to any organized system). The Romans originally had a calendar of 10 months, but subsequently adopted the Etruscan calendar of 12 months, with 28, 29 or 31 days each; corrections were made by intercalating a ‘month’ of 22 or 23 days between the 23rd and 24th February. However, this was so inefficient that by the time of Julius Caesar the civil calendar was three months ahead of the solar In the year 46 bc Caesar corrected this by having a year of 445 days (known as the ‘ultimus annus confusion^ or ‘the last year of the muddled reckoning’). He then adapted the Egyptian solar calendar for Roman use, inserting extra days in the shorter months to bring the total up to 365, with the addition of a single day between the 23rd and 24th February in leap years. This calendar, known as the Julian Calendar, remained in use until the time of Gregory XIII in 1582, who made a further correction (of eleven days) and instituted the calendar which is in general use today. A complex calendrical system was the hallmark of many Mesoamerican societies, but it found its extreme expression among the Maya. It seems, however, to have been introduced by the Olmec some time in the Pre-Classic (seeTRES Zapotes and Chiapa De Corzo). Two calendars were in use in both the Maya and later the Aztec cultures. The Sacred Calendar was 260 days long and consisted of 13 months of 20 days; the Solar Calendar of 365 days was made up of 18 months of 20 days plus five extra (regarded as unlucky) days. These two calendars were integrated so that any given day would only occur once in 52 years. Known as the Calendar Round, it is best visualized as a pair of meshing gears of 260 and 365 teeth respectively, where, if a line were marked on them at the initial point of their meshing, it would take 52 revolutions of the larger one to restore the gears to their original relationship. Far more useful to archaeologists is the Maya Long Count or Initial Series, which was a means of recording absolute time. Its starting date of 3113 bc (using the Goodman-Thompson-Martinez correlation) marks some mythical event in Maya history and itself stands at the beginning of a cycle 13 Baktuns long. A Baktun at 144,000 days is the largest unit of time in the This is further divided into smaller units: the Katun (7200 days); the Tun (360 days); the Uinal (20 days) and the Kin (a single day). Thus Long Count dates are expressed in terms of these units in a five place notation. Therefore the date 9.18.0.0.0. indicates the passage of 9 X 144,000 plus 18 X 7200 days since the initial date of 3113 bc. In cultural contexts, however, the dates are inscribed as a series of hieroglyphs which incorporate numeration via bars (units of five) and dots (units of one). Short Count dating replaces the Long Count after AD 900 and although based on a similar system, the Katun replaces the Baktun as the largest unit. Unfortunately, it is a good deal less precise from the point of view of the archaeologist. Its imprecise nature is best understood by analogy with our own habit of recording only the last two digits of the year, for example ’82: such a date, of course, can be interpreted as 1882 or 1982. The Secondary Series is a means of correcting the quarter day error in the 365-day Solar Year (i.e. the equivalent of our leap year). As an addendum to calendar dates inscribed on stelae, the Secondary Series records the number of days by which the inscribed date was out of synchronization with the actual 52-year cycle of the Calendar Round. Other calendars, based on long-term observations of heavenly bodies (see astronomy), were used as a means of predicting events. Many aspects of daily life were regulated by the calendar, with certain periods being considered dangerous or unlucky. The five odd days of the Solar Year, for instance, were unlucky days, while the completion of any Calendar Round was a particularly dangerous time, since it was believed that the end of the world would come at just such a time.