Year

A year is a unit of time, generally consisting of dozens to hundreds of days. The exact definition varies within different worlds or universes, but years are usually defined either by climatic cycles or by the motion of astronomical bodies—or by both where, is as often the case, the two are tied together. On magical worlds, they may also be defined by cyclical changes in enchantments or planar phenomena. Where there are no obvious such cycles to draw on, instead a year may be simply defined as some fixed but arbitrary number of days. On geotic worlds, a year is typically about seven or eight orders of magnitude larger than a second, such that a normal human lifetime is generally measured in some tens of years.

The most common adjective to refer to years is "annual".

Though the abbreviation "y" or "yr" is commonly used for years, some authorities prefer the use of "a", for the Latin root annus, meaning year (the same word, of course, that gives rise to the adjective "annual"). For times before the present, the abbreviations "mya" for "millions of years ago", "bya" for "billions of years ago", and so on are common, though they are discouraged by some authorities.

Definitions

The length of a year may be based on any convenient cycle; many if not most terrestrial worlds have some sort of regular transition or phenomenon with a period of the appropriate order of magnitude. Often the basis of the year is astronomical; it may be based on the motion or apparent motion of a sun or a star (or all the stars, if they move together), or in some cases on a moon or on some other more obscure body. It may also be climatic, based on regular and predictable cycles of temperature, precipitation, winds, or other aspects of the weather. On some magical worlds the basis of the year may be stœcheiotic, deriving from some rhegus or hapantic (or, much less commonly, an epasma on a prominent object or person) that changes regularly in magnitude or in effect. Sometimes the inhabitants of a world of a dynamic chorade may base the length of their years on cycles in the arrangement of the planes, if this is something that has a significant effect on the lives of its inhabitants. (Such a year is called a choric year.) It's common within a universe for all the worlds to use the same definition of a year, though the length of a year on different worlds may vary, and there may be some unusual worlds that are exceptions, either because they lack the cyclic phenomenon that defines the year elsewhere in the universe, or because they sport some additional cyclic phenomenon that is more prominent.

It often happens that there are multiple cycles on a world that are nearly but not exactly the same length. In that case, there may be multiple definitions of the year, close enough to be interchangeable in most contexts, but different enough that for technical or precise calculations and operations a particular definition must be chosen. Different definitions of the year may be common among different cultures or religions, for example, or one definition may be used by scientists and scholars and another by laymen. The inaccordance in the different year measurements may lead to deviations called epacts when an occasion defined by one version of the year is placed within a year measured by another method.

Herit

On Earth and other planets of Herit, as well as in certain other universes with similar cosmologies, a year is most commonly defined as the time it takes for the planet to orbit its sun. This means, of course, that some planets will have much longer years than others; in the Solar system, for instance, a year on Neptune is about 165 times a Terran year, while a Mercury year is only about one fifth of a Terran year.

As described above, however, there are other ways that years can be measured. The time that it takes a planet to complete one orbit, relative to an external frame of reference such as the fixed stars, is called the sidereal year. But for a planet with an axial tilt, such as the Earth, the sun seems to move north and south in the sky over the course of the year, and it may seem logical to define the year as the time it takes the sun to return to its original apparent position. Because of axial precession, this time is not the same as the sidereal year; the period of the apparent motion of the sun is called the solar year, or tropical year, or equinoctial year. For the Earth, the sidereal year and tropical year differ only by a little over twenty minutes, less than 0.004 percent of the year's length. For Neptune, however, the sidereal year is equal to about 60,189 (Earth) days and the solar year to about 59,800, a difference of more than 0.6%—still small overall, perhaps, but more than two orders of magnitude larger than the relative difference between the two year measurements on Earth. Yet another way that years can be measured is by the time between periastra, the closest passages between the planet and the star it orbits. The year so measured, called the anomalistic year, is again usually close but not identical to the sidereal and the solar years, in Earth's case exceeding the sidereal year by about four and three quarters minutes. The Julian year used by scientists, meanwhile, is not exactly equal to any of these years, but is defined arbitrarily as exactly 31,557,600 metric seconds (365.25 days of 86,400 seconds each); this falls in between Earth's tropical and sidereal years, though a bit closer to the latter.

Subdivisions

On most worlds, a year is composed of some number of days—on terrestrial worlds, that number is usually somewhere between fifty and a thousand. The may in turn be divided into hours, minutes, and so on. Very often, however, there are also intermediate time units in common use, larger than a day but smaller than a year.

Where the year corresponds to some climatic cycle, this cycle leads to natural subdivisions, called seasons. For example, many worlds (including Earth) have four seasons: winter, when nights are long and the temperature is relatively cold; spring, a time of increasing warmth and daylight often associated with growth and new beginnings; summer, when the days are long and the temperatures are hottest, and fall, or autumn, when the days are shortening, the temperature begins to fall, and deciduous trees lose their leaves. Other worlds may have more or fewer seasons, either adding to or subtracting from the Terran tetrad or calling them by entirely different names. The divisions between the seasons are not necessarily clear-cut; they more often transition gradually into each other rather than change suddenly, and even different cultures on the same world that reckon with the same seasons—or different people within a culture—might use different conventions as to exactly when one season ends and the next begins. It's also possible for different parts of the world to experience the seasons differently; on Earth and other Heritic planets, for instance, where the northern hemisphere is in summer the southern is in winter, and vice versa (and likewise for spring and autumn), while on the equator there are effectively no seasons at all.

On some worlds, there is no natural annual cycle due to astronomical phenomena, but there are cycles of widespread or even worldwide changes brought about through some rhegus or other magical effect. The periods of different stœcheiotic conditions are often called mesters; a world with such a cycle is called a mestral world. On a mestral world the mesters are, in fact, frequently the primary superdiurnal divisions of the year. Mesters are somewhat more likely than seasons to have abrupt transitions, though this isn't always the case; on some mestral worlds the conditions change gradually between one mester and the next.

A more arbitrary common subdivision of the year is into four equal or nearly equal parts; these quarter-years are often known simply as quarters—or, primarily in Scotland, as "raiths". Such subdivisions are especially used in economic and business contexts, when profits and losses are often tracked by quarters and quarterly reports are issued; and in academic contexts, when many universities and other schools may have their class schedules arranged by quarters. Of course, this is not universal, and on some worlds businesses or universities may instead refer to thirds of a year, or fifths, or other divisions. The popular use of quarters may be connected to the fact that many worlds have four seasons (though the quarters and seasons do not necessarily exactly correspond), but such quarterly systems are also in use on many worlds that lack seasons, or have some other number of seasons per year, so this isn't the full explanation.

A system of naming and tracking days within a year, along with the labeling and tracking of the passage of the years themselves, is called a calendar; a specific day as designated by a the calendar is called a calendar date (or just a date). While it's possible for the days within a year to just be numbered from one to the total number of days in the year, more commonly the days are named in terms of the higher divisions: weeks, months, seasons, mesters, or whatever is in use. The days may be numbered starting from one within each month or season, or within each week within a month; or the days within a month may be given unique names. There is an endless variety of possible ways to organize the days within a year, and different calendars may use very different methods.

Leap years and lag years

While it's convenient to divide a year into days, it often happens that the year does not actually equal an integral number of days. There are several ways to account for the discrepancy. It's possible to just have one day of the year (usually the last day) slightly shorter or longer to make up for the difference. The primary problem with this method in worlds with a day-night cycle is that if the days are not of a consistent length, the beginning of the day will not always coincide with the same part of the day-night cycle. While the day may begin at midnight one year, the slightly longer or shorter day will push that time backward or forward slightly, until after many years enough of those changes may have accumulated that the day is now beginning at noon.

More commonly, some years are afforded more or fewer days— perhaps just one day at regular or irregular intervals, perhaps an entire extra or omitted week or month at lower frequency. A year with extra days is called a leap year; one with days removed is called a lag year. Generally, a calendar will have leap years or lag years, but not both, but there are some rare calendars that have both leap years and lag years at different intervals to achieve the correct ratio.

Larger units

Just as the year is often subdivided into smaller intervals, so too do people often find it useful to name larger units comprising multiple years. Common terms for such periods—at least in areas using decimal number systems—involve powers of ten. Ten years is a decade, a hundred a century, a thousand a millennium (or, less often, a chiliad or milliad). In geology and astronomy, the word "æon" is in use to signify one billion years. Other periods that have seen use include the lustrum, or lustre (a period of five years in the Roman census); the katun (a twenty-year period in the Maya calendar); the jubilee (a period of fifty years; originating in a Jewish commemoration laid out in the book of Leviticus but for a time used generally to signify a half century before passing into more general use of any anniversary or occasion of celebration); the Sothic cycle, or Canicular period (a period of 1460 years in use by the ancient Egyptians); and the saros (originally, in Babylonia, a period of 3600 years, though the word is in use in modern astronomy to refer to the 18⅔ year period of the cycle of eclipses). There are Latinate general terms for periods of multiple years—three years is a triennium, four a quadrennium, five a quinquennium, six a sexennium, seven a septennium, and so on—but they are in most places not in common use. (Like "millennium", all of these words can pluralize by changing the -ium to -a: triennia, quadrennia, quinquennia, sexennia, septennia.) Other words exist for certain numbers of years, but are likewise rarely used or obsolete, or confined mostly to particular contexts—a period of five years has been called a quinquennal; a period of seven years has been called a septinary, a septimane, or, in certain historical contexts, a septennate (or, formerly, a "week", though this word now applies almost exclusively to a period of seven days); a period of eleven years can be called a hendecad, and one of twelve a duodecad; and so forth.

For much larger units of time, it's common for fixed numbers of years to be deprecated in favor of time periods, usually of irregular durations, based on major geological, astronomical, or stœcheiotic changes. The several billion years of Earth's prehistory, for instance, are divided into three or four unequal eons, ranging from about half a billion to almost two billion years in length. (Not to be confused with the astronomical æon, which may also be spelled "eon", in which case the distinction often must come from context.) The eons are in turn subdivided into eras, which are divided into periods, then epochs, then ages. For example, the famous extinction of the non-avian dinosaurs occurred at the end of the Maastrichtian Age (about 72 to 66 mya), which was part of the Late Cretaceous epoch (100.5 to 66 mya) of the Cretaceous Period (145 to 66 mya) of the Mesozoic Era (252 to 66 mya), which itself was part of the Phanerozoic Eon (538.8 mya to present).

Large numbers of years can also be designated by applying the metric prefixes to the Latin annus. A millennium can therefore be called a kiloannus or kilannus, and abbreviated ka; a million years would be a megaannus or megannus, abbreviated Ma; and so on through a gigaannus or gigannus (Ga), a teraannus or terannus (Ta), a petaannus or petannus (Pa), an exaannus or exannus (Ea), a zettaannus or zettannus (Za), a yottaannus or yottannus (Ya), a ronnaannus or ronnannus (Ra), and a quettaannus or quettannus (Qa). These words are pluralized by changing the "annus" to "anni", so for instance the plural of megannus would be meganni, although the full words are much less often used than the abbreviations. Of course, the largest of these units have limited utility; a terannus is already seventy times the age of Herit, so it's difficult to come up with serious situations in which it would be useful to measure times in petanni or exanni, let alone ronnanni or quettanni.

Nomenclature

There are some worlds where every year is given its own name. Sometimes these names are arbitrary or based on some preset pattern, but sometimes they are based on significant events of that year. Of course, this works better for past years than for future, unless one possesses the gift of prophecy, but there's less occasion to refer to future years anyway, and if it is necessary to do so, they can simply be specified in relation to the present or past years, such as "Seven years from the current year", or "A hundred years from the year of the Death of Winter."

More often, instead of or in addition to names, the years are simply labeled with consecutive numbers. This has several advantages over the name system: it makes it as easy to refer to specific future years as to past; it does not require separate memorization of a name for each year; and it makes it very easy to determine the distance between two years—just subtract the numbers.

Year Zero

If the years are numbered, then the numbering has to start somewhere. The beginning of the numbering system is called the year zero (or, less commonly, the zero year). For very young worlds (or worlds that are believed to be young), year zero may be the year of the (supposed) creation of the world, but more often this year is either unknown or too long ago to serve as a convenient reference point, and/or the formation of the world occurred too gradually to be ascribed to a single year. Instead, the zero year is often set as the year of some event of historical or religious significance—the foundation of an empire, the birth of a great leader, and so on.

This does pose a potential challenge when speaking of historical events before the zero year. It's possible to label the years before year zero with negative numbers, so that for instance three hundred years before year zero is the year -300, but this is uncommon. More usually, any potential ambiguity is resolved by adding some clarifying word or abbreviation. In the Drithidian calendar of Dadauar, for instance, years before year zero are marked with a "V"; years after year zero are usually unmarked, but where that might lead to confusion they are designated with an "N".

Note that not all calendars have a literal zero year—in some calendars the year count jumps straight from "negative one" to year one, and there may be no year that corresponds to the number zero. This is true of the Julian calendar common on Earth; 1 CE directly follows 1 BCE, with no year zero in between. It still may be convenient, if not quite accurate, to refer to the year before year one as the zero year, but in any case in such calendars it is usually year one that marks the event the calendar is founded on. Year one of the Julian calendar, for instance, is the year the calendar's creators believed the religious figure Jesus Christ was born, although the consensus of modern historians is that their dating was inaccurate and his birth was probably actually several years earlier.

It is possible, though rare, for year zero to be in the future, and for the year numbering to count downward toward that future year. This may be because of some prophecy of a future event, or it may emphasize a lofty goal that some ruler or government has set. In any case, once that year zero is passed, if the same calendar is still used, generally the years start counting up normally.

Cyclic calendars

Instead of starting at a unique year zero, it's also possible for the years to be counted in cycles. After the year count has reached some particular number, it starts again at zero or one—or, if the years are named instead of numbered, there is a fixed sequence of names that restarts once exhausted. In such cyclic calendars, if it's necessary to refer to events outside the current cycle then the cycles themselves must be named or numbered—and, if numbered, there must perforce be some "cycle zero" (or cycle one). It is possible for a calendar to have multiple levels of cycles, but the longer cycles rarely become important unless each cycle is very short or one is dealing with times in the very distant past or future.

Anniversaries and commemorations

The recurrence of the calendar date on which some event occurred in a past year is called the event's anniversary. The anniversary after some particular number of years can be specified by a prefix attached to the morpheme "-ennial"; the biennial anniversary would be two years after the event in question, the triennial after three, the quadriennial after four, and so on. (These words can be used either as adjectives, referring to events that recur after or have a duration of the designated number of years, or as nouns, referring to the corresponding anniversary.) Of course, in general people place more significance on anniversaries after more time has passed, so these words are less used than those that represent a larger number of years: the decennial after ten years, the centennial after a hundred, the quasquicentennial after 125, the sesquicentennial after 150, the bicentennial after two hundred, the tricentennial after three, and so on. In principle, perhaps one could refer to a half-year anniversary as a semiennial, but in practice such fractional anniversaries aren't in common use on most worlds.

In addition to referring to years in general, the adjective "annual" can also mean "occurring once a year". ("Solennial" and "solennic" are synonyms for "annual" in this context, though neither has ever been in common use on Earth.) Prefixes may be used to specify events or commemorations that occur multiple times a year, or every few years; a "biannual" event would occur every two years, for instance, or a "semiannual" event would be every half a year—that is, twice a year.

Anniversaries of significant events may be commemorated each year with celebrations and ceremonies. This may happen on both the personal and the cultural, national, or international scale. In many cultures, for instance, people celebrate their birthdays, the anniversaries of the day they were born... and measure their age in years. (Of course, this may not hold for creatures of drastically different lifespans than humans.) Other such personal annual commemorations include wedding anniversaries—the anniversary of one's marriage—and, among folks that undergo metamorphosis, the anniversary of that metamorphosis, or of its beginning or end if it extends over multiple days. Among the most common names for the latter type of anniversary are a changing day, or a day of emergence.

More widely observed annual celebrations are known as holidays. One very common holiday is the first day of the year, often seen as a time of renewal and new beginnings. The time chosen as the beginning of the year is, of course, generally arbitrary; in the Julian calendar of Earth the year begins shortly after midwinter (in the northern hemisphere), for example, but the Jewish calendar year begins near the fall equinox, and the Buddhist and Hindu calendar years in the spring. Where seasonal or astronomical changes exist, holidays and festivities may also be based on particular times of year such as midwinter, midsummer, solstices, or equinoctes, especially in preindustrial societies based largely around agriculture. Other holidays are commonly based on religious commemmorations or on the birthdates of venerated figures or the anniversaries of national independence or other days of historical significance. Indeed, the English word "holiday" derives from the first; etymologically, a "holiday" was originally a "holy day".

Usage in the Wongery

When the word "year" is used in the Wongery in an article about a particular world or something specific to a particular world, it generally means a year as defined on that world. Otherwise, when the word "year" is used without further context, it usually refers to a Julian year, which again is equal to exactly 31,557,600 seconds.

See also

• Year on Wikipedia