A year is the period of Earth's orbit that moves in its orbit around the Sun. Because of the axis of the Earth's axis, a year's journey sees the passing of seasons, characterized by changes in weather, daylight hours, and, consequently, vegetation and soil fertility. In temperate and subpolar areas throughout the planet, four seasons are commonly known: spring, summer, autumn and winter . In the tropics and subtropics, some geographic sectors do not present the specified seasons; but in the seasonal tropics, the annual wet season wet and dry are recognized and tracked. This year is 2018.
One calendar year is the approximate number of days from the Earth's orbital period as calculated in the given calendar. The Gregorian calendar, or modern, presents its calendar year to 365 days or leap year 366 days, such as the Julian calendar; see below. For the Gregorian calendar, the average length of the calendar year (year on average) throughout the complete 400-year jump cycle is 365.2425 days. ISO ISO 80000-3 standard, Appendix C, supports the symbol "a" (for Latin annus ) to represent either 365 or 366 days of the year. In English, abbreviations "y" and "yr" are usually used.
In astronomy, Julian is the unit of time; it is defined as 365.25 days precisely 86,400 seconds (SI base unit), with a total of exactly 31,557,600 seconds in the Julian astronomical year.
The word "year" is also used for periods loosely associated with, but not synonymous with, calendar or astronomical years, such as the seasonal year, fiscal year, academic year, etc. Similarly, "year" can mean any planetary period orbitals: for example, the year of Mars or the year of Venus is an example of the time it takes for planets to transit a complete orbit. This term may also be used in reference to any period or long cycle, such as Great Year .
Video Year
Etimologi
English year (via West Saxon ar (/j? Ar/) , Anglian ?? r ) continue Proto-Germanic * j? Ran ( * j ?? ran ). Cognates is German
annus is a single accusative; ann? is a single and nominative genitive; ann? datif and ablatif tunggal) adalah dari kata benda PIE * h? et-no - , which also produces Gothic aÃÆ'¾n "years" (only superficial plural aønnam ).
Although most languages ​​treat these words as thematic * yeh? Ro - , there is evidence for the original derivative with the suffix * - r/n , * yeh? -ro - . The two Indo-European words for the year, * yeh? -ro - and * h? Et-no - , then it will come from the root which means "to go, move", * h? ey - and * h? et - , respectively (compare Vedic Sanskrit ÃÆ'Â © ti "go", overtake "You go, crashed"). A number of English words come from the Latin annus , such as annual, annuities, birthdays, etc.; per year means "every year", anno Domini means "in God's year".
The Greek word for "year", ???? , corresponding to the Latin vetus "old", from the word PIE * wetos - "year", is also preserved in this sense in Sanskrit vat "year" and "vat-sa - " yearling (calf) ", the latter is also reflected in the Latin vitulus " bull cow " English what is "ram" (Old English weÃÆ' Â ° er , Gothic wiÃÆ'¾rus "sheep").
In some languages, it is common to count the year by referring to one season, as in "summer", or "winter", or "harvest season". Examples include Chinese? "year", initially, an ideographic compound someone carries a bundle of wheat that shows "harvest". Slavic other than god? "time period; year" using l? Go to "summer, year".
In the International Quantity System (ISO 80000-3), the year (symbol, a ) is defined as 365 days or 366 days.
Maps Year
Interactions
No astronomical year has an integer number of days or lunar months, so any calendar that follows astronomical year must have an intercalation system such as a leap year.
Julian Calendar
In the Julian calendar, the average (average) length of the year is 365.25 days. In the non-leap year, there were 365 days, in a leap year there were 366 days. The leap year occurs every fourth year, or leap year, in which a leap day is integrated into February. The name "Leap Day" applies to the added day.
The revised Julian calendar, proposed in 1923 and used in some Eastern Orthodox Churches, has 218 leap years every 900 years, for an average (long) year 365.242 2222 day, close to the average length of the tropical year, 365.242 19 days (relative error 9Ã, Â · 10 -8 ). In 2800 CE, the Julian Gregorian and Revised calendars will begin differing from one calendar day.
Gregorian Calendar
The Gregorian calendar seeks to cause the equinox northward to fall or shortly before 21 March and therefore follow the northern equinox year, or the tropical year. Since 97 of the 400 years are leap years, the average length of the Gregorian calendar year is 365.242 5 days; with a relative error below one ppm (8 Â · 10 -7 ) relative to the current length of the tropical year on average ( 365.242 19 day) and even closer to the current equinox year year 365,242 374 you want to match. It is estimated that in AD 4000, the northern equinox will fall back on a single day in the Gregorian calendar, not because of this difference, but because of the slowing of the Earth's rotation and the lengthening of the associated day.
Other calendars
Historically, the lunisolar calendar intercrossed the entire leap month on the basis of observation. The Lunisolar calendar is largely unused except for liturgical reasons (Hebrew calendar, various Hindu calendars).
The modern adaptation of the historical Jalali calendar, known as the Hijri calendar (1925), is a pure solar calendar with an irregular jump pattern based on observations (or astronomical calculations), aimed at placing the new year (Nowruz) on vernal equinox ( for the Tehran timezone), compared with using a leap year algorithmic system.
Year numbering
The calendar era sets the cardinal number for each successive year, using reference points in the past as the beginning of the era.
The global standard is the Anno Domini era (but the Common Era label is preferred by some). It was historically introduced in the 6th century and is meant to count the years from the birth of Jesus.
The Anno Domini era is abbreviated as Latin AD (for Anno Domini "in the year of God"), or an alternate CE for "Common Era." The year before AD 1 is abbreviated BC for Before Christ or alternate BC for Prior to the General Era The year number is based on inclusive counting, there is no "zero year". In modern alternative calculations the number of years of Astronomy, the positive numbers indicate AD year, the number 0 denotes 1 BC, -1 indicates 2 BC, and so on.
Pragmatic division
Financial and scientific calculations often use the 365 day calendar to simplify daily rates.
Fiscal year
The fiscal or financial year is a 12-month period used to calculate the annual financial statements in other businesses and organizations. In many jurisdictions, accounting rules require such a report once every twelve months, but do not require that twelve months be a calendar year.
For example, in Canada and India the fiscal year runs from April 1; in the United Kingdom runs from 1 April for corporate tax purposes and government financial statements, but from April 6 for personal tax purposes and state benefit payments; in Australia takes place from 1 July; while in the United States the federal government's fiscal year runs from 1 October.
Academic year
The academic year is an annual period in which a student attends an educational institution. The academic year can be divided into academic terms, such as semesters or quarters. School years in many countries start in August or September and end in May, June or July. In Israel the academic year begins around October or November, in harmony with the second month of the Hebrew Calendar.
Some schools in the UK and the US divide the academic year into three roughly the same length (called trimester or quarterly in the US), coincidentally coincide with autumn, winter, and spring. In some, short summer sessions, sometimes regarded as part of a regular academic year, attended by students voluntarily or electively. Other schools break the year into two main semesters, the first (usually August to December) and the second semester (January to May). Each of these major semesters can be split into half with medium term exams, and each section is referred to as quarter (or term in some countries). There may also be voluntary summer sessions and/or short sessions in January.
Some other schools, including some in the United States, have four marking periods. Some schools in the United States, especially Boston Latin School, can divide this year into five or more marking periods. Some countries are in this defense that there may be a positive correlation between report frequency and academic achievement.
There are typically 180 days of teaching each year in schools in the United States, excluding weekends and breaks, while there are 190 days for students in Canadian, New Zealand and British public schools, and 200 for students in Australia.
In India the academic year usually begins from June 1 and ends on 31 May. Although schools begin to close from mid-March, the actual academic closing is on May 31 and in Nepal starting from July 15th.
Australian schools and universities typically have an academic year that is roughly parallel to the calendar year (ie, starting February or March and ending in October to December), as the southern hemisphere has summer from December to February.
Year astronomy
Julian
The Julian Year, as used in astronomy and other sciences, is a unit of time defined as exactly 365.25 days. This is the normal meaning of the "year" unit (the "a" symbol of the Latin annus ) used in various scientific contexts. The Julian Age 36 525 Days and the millennium Julian 365 250 days are used in astronomical calculations. Essentially, stating the time interval in the Julian years is a way to precisely determine how many days (not how many "real" years), for long time intervals in which the number of days will be heavy and not intuitive. By convention, the Julian year is used in the calculation of distances covered by light years.
In the Integrated Code for Units of Size, the symbol, a (without subscripts), always refers to Julian, a j , of exact 31 557 600 seconds.
- 365.25 days 86 400 seconds = 1 a = 1 a j = 31.5576 Ms
The multiplier prefix SI can be applied to form ka (kiloannus), Ma (megaannus), etc.
Year sidereal, tropical, and anomalistic
Draconic yearThe draconic year, the year of drafts, the ecliptic year, or the ecliptic year is the time taken for the Sun (as seen from Earth) to complete a revolution in relation to the same moon node (the point at which the Moon's orbit cuts the ecliptic). This year is related to eclipse: this happens only when the Sun and the Moon are near this knot; So the eclipse takes place in about a month every half year of eclipse. Therefore there are two eclipse seasons each year of eclipse. The average duration of an eclipse year is
- 346.620 075 883 day (346 d 14 hours 52 min 54 s) (on epoch J2000.0).
This term is sometimes incorrectly used for the lunar pronunciation or nodal period of precession, ie the complete revolution period of the Moon rising node around the ecliptic: 18612 815 932 Julian years ( 6 798 .331 019 days; on epoch J2000.0).
Full Moon Cycle
The full moon cycle is the time for the Sun (as seen from Earth) to complete a revolution against the perigee orbit of the Moon. This period is associated with the size of the full moon, and also with the duration of different synodic moons. Duration of one full moon cycle is:
- 411.784 430 29 day (411 days 18 hours 49 minutes 34 seconds) (on epoch J2000.0).
Lunar year
The lunar year consists of twelve full cycles of the Moon phase, as seen from Earth. It has a duration of about 354.37 days. Muslims use this to celebrate their Idul Fitri and to mark the beginning of the fasting month of Ramadan. One Muslim calendar year is based on the lunar cycle.
Year is not clear
The faint year, of the annus vagus, or the nomad year, is an integral estimate for a year equal to 365 days, which wanders in relation to more precise years. Usually the year is vaguely divided into 12 months schematic of 30 days each plus 5 days epagomenal. The year is vaguely used in the calendar of Ancient Egypt, Iran, Armenia and in Mesoamerica among Aztec and Maya tribes. It is still used by many Zoroastrian communities.
Heliacal Year
The heliacal year is the interval between heliacal risings of a star. This differs from the sidereal year for the distant stars of the ecliptic mainly due to the precession of the equinox.
Sothic Year
The Sothic year is the interval between the heliacal risings of the star Sirius. Currently less than a sidereal year and its duration is very close to Julian's year of 365.25 days.
Gaussian Year
The Gaussian Year is a sidereal year for a planet with a negligible mass (relative to the Sun) and is not disturbed by any other planet governed by the Gaussian gravity constant. Such a planet would be a little closer to the Sun than the Earth's average distance. The length is:
- 365.256 8983 day (365 days 6 hours 9 minutes 56 seconds). Besselian_year "> Besselian year
- B = 1900.0 (date Julian TT - 2 415 020 .313 52 )/ 365.242 198 781
- The position of the equinox points and the solstice with respect to the parts of the Earth's orbit change: the equinox and solstis move westward relative to the stars due to precession, and the apsides move in the other direction because of the long-term effects the length of gravitational attraction by other planets. Since the Earth's velocity varies according to its position in its orbit as measured from its perihelion, the Earth's velocity when at the solstice or the equinox point changes over time: if the point moves toward the perihelion, the interval between two parts decreases slightly from year to year; if the point moves toward the aphelion, that period increases slightly from year to year. Thus the "tropical year" measured from one part of the northern ("vernal") equinox to the next, is different from that measured between the alleys of the south ("fall") equinox. The averages above the full orbit do not change because of this, so the average length of the tropical year does not change because of this second-order effect.
- Every planetary motion is disturbed by the gravity of every other planet. This causes short-term fluctuations in speed, and therefore the period from year to year. In addition, this causes long-term changes in its orbit, and therefore long-term changes in this period.
- Tidal drag between the Earth and the Moon and the Sun increases the length of the day and month (by transferring the angular momentum from the Earth's rotation to the Moon's revolution); since a clear sun day means is the unit that we measure the length of the year in civil life, the length of the year seems to decrease. The rate of Earth rotation is also altered by factors such as post-glacial rebound and sea level rise.
- a t = 365.242 19 day for the average tropical year;
- a j = 365.25 days for the average of the Julian year;
- days g = 365.2425 for the average Gregorian year;
- a , without qualification = 1 a j ;
- and, ar because is , is a unit area.
- a = 31 556 925 .445 seconds (approximately 365.242 192 65 ephemeris days)
- ka (for kiloannum) - - units of time equal to one thousand, or 10 3 , years, or 1 E3 years, also known as the millennium in anthropology and the use of calendars. The prefix "ka" is usually used in geology, paleontology, and archeology for the Holocene and Pleistocene periods, where non-radiocarbon dating techniques: eg ice core dating, dendrochronology, uranium-thorium dating, or varve analysis; used as the main dating method for age determination. If age is strongly determined by radiocarbon dating, then age should be expressed in radiocarbon or calendar (calibrated) years Before There.
- Ma (for megaannum) - a time unit equal to one million, or 10 6 , year, or 1 year E6. The suffix "Ma" is commonly used in disciplines such as geology, paleontology, and celestial mechanics to signify very long periods of time to the past or future. For example, the dinosaur species Tyrannosaurus rex overflows about 66 Ma (66 million years ago). The term "then" may not always be indicated: if the quantity of duration is determined while not explicitly specifying the time period, one can assume that "then" is implied; alternative units "mya" include "then" explicitly. It is also written as "million years" (in the past) in works for the public good. In astronomy applications, the year used is the Julian year precisely 365.25 days. In geology and paleontology, this year is not so precise and varies depending on the author.
- Ga (for a gigaannum) - a time unit equal to 10 9 years, or a billion years. "Ga" is commonly used in disciplines such as cosmology and geology to signify a very long period of time in the past. For example, Earth formation occurs about 4.54 Ga (4.54 billion years ago).
- Ta (for an update) - a time unit equal to 10 12 years, or a trillion years. "Ta" is a very long unit of time, about 70 times as long as the age of the universe. This is an order as large as the expected life span of a small red dwarf.
- Pa (for petaannum) - a time unit equal to 10 15 year, or one quadrillion years. The half-life of cadmium-113 nuclides is about 8 Pa. This symbol coincides with it for pascal without the multiplier prefix, although both are rarely used and the context will usually be sufficient to distinguish the timing of the pressure value.
- Ea (for exaannum) - a time unit equal to 10 18 years, or one quintillion years. Tungsten-180 half-life is 1.8 Ea.
The Besselian year is a tropical year that begins when (fictitious) Sun means reaching the ecliptic longitude of 280 °. This time or on January 1st. Named from German astronomer and mathematician, Friedrich Bessel of the 19th century. The following equations can be used to calculate the current Besselian period (in a few years):
The TT subscript shows that for this formula, the Julian date should use a Terrestrial Time scale, or its predecessor, ephemeris time.
Variations throughout the year and days
The exact length of the year astronomy changes over time.
Numerical year variation value
The average year length in this section is calculated for the year 2000, and the year-length difference, compared to 2000, is given for previous and future years. In a day table is 86,400 seconds long SI.
Summary
The average one-year Gregorian is 365,2425 days (52,175 weeks, 8 765 .82 clock, 525 949 .2 min or 31 556 952 seconds). For this calendar, the common year is 365 days ( 8760 hour, 525 600 minute or 31 536 000 second), and the leap year is 366 days ( 8784 hour, 527 040 minutes 31 622 400 seconds). The 400-year Gregorian calendar cycle has 146 097 days and is therefore exactly 20 871 weeks.
"Greater" astronomical year
Equinoctial Cycle
The Great Year, or the equinoctial cycle, according to the complete revolution of the equinoxes around the ecliptic. The length is about 25,700 years, and can not be determined quite precisely, because the speed of precession depends on too many factors, causing unpredictable variations.
Galaxy Year
The Galaxy Year is the time it takes the solar system to spin once around the galactic center. It consists of about 230 million Earth years.
Season year
A seasonal year is the time between successive recursion of seasonal events such as river floods, migratory bird species, flowering of plant species, first frost, or the first scheduled match of a particular sport.. All of these events can have wide variations over a month from year to year.
Symbol
In the International Quantity System the symbol for the year as the unit of time is a , taken from the Latin annus .
In English, the abbreviations "y" or "yr" are more commonly used in non-scientific literature, but also specifically in geology and paleontology, where "kyr, myr, byr" (thousands, millions, and billions of years, respectively) and similar abbreviations are used to indicate time intervals that are far from now.
Symbol
NIST SP811 and ISO 80000-3: 2006 support the a symbol as a time unit for one year. In English, abbreviations y and yr are also used.
The Unified Code for Units of Measure disambiguates the various symbologies of ISO 1000, ISO 2955 and ANSI X3.50 by using:
Where:
The International Union of Pure and Applied Chemistry (IUPAC) and the International Geological Association have jointly recommended defining annus, with symbols a , such as the length of the tropical year in 2000:
This is different from the definition above 365.25 days about 20 parts per million. The joint document says that definitions such as Julian's year "bear pre-programmed obsolescence, due to variability in the Earth's orbital motion," but then propose using the length of the tropical year in 2000 AD (determined to milliseconds.), Which suffer from the same problem. (The tropical year oscillates with more than a minute.)
This notation proved controversial because it contradicts previous conventions among geoscientists to use a specifically for last year , and y or yr for a period of one year.
prefix SI prefix
For the following, there are alternative forms of successive vowel elics, such as kilannus , megannus , etc. Exponential exponentials and notations are typically used to calculate and display calculations, and to save space, as in data tables.
Abbreviations yr and yes
In astronomy, geology, and paleontology, the abbreviation of yr during years and yes during many years ago is sometimes used, combined with the prefix for a thousand, million, or billion. They are not SI units, using y to abbreviate the English "year" but following the ambiguous international recommendations, use the first standard English letters as prefix (t, m, and b) or the metric prefix (k , M, and G) or variations in the metric prefix (k, m, g). In archeology, dealing with a more recent period, the date normally expressed, for example "22,000 years ago" can be used as an easier equivalent of the Prior To Date ("BP").
These abbreviations include:
The use of mya and bya has been left behind in modern geophysics, the recommended uses are Ma and Ga for Prior to Attend, but "me" for the duration of the time. This "ad hoc" difference between this "absolute" time and time interval is somewhat controversial among members of the Geological Society of America.
Note that on the chart using the yes unit on the horizontal axis, the time flows from right to left, which may seem counter-intuitive. If the yes unit is on the vertical axis, the time flows from top to bottom which may be more easily understood than conventional notation.
See also
References
Note
Further reading
Fraser, Julius Thomas (1987). Time, Foreign Stranger (illustration ed.). Amherst: University of Massachusetts Press. ISBNÃ, 0-87023-576-1. OCLCÃ, 15790499.
External links
- Year image
Source of the article : Wikipedia
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