This post is followed,at the end, by an Appendix on Timing system(Local,Standard and Sidereal time)
Present day Chinese calendar is a byproduct of long evolutionary process. Like in other part of the world Officially China uses the usual Gregorian Calendar. The Gregorian Calendar was adopted on January 1912 as official calendar. But traditionally the old Chinese Calendar is still in vogue for religious and festival purposes. But the old Traditional calendar has been replaced by a new Simplified version of the same. The earliest evidence of the Chinese Lunar Calendar is found to be around Shang Dynasty (around 1600 BC-). –
It is a Luni-solar calendar depending upon phases of moon. The year consists of 354 days, as usually in contrast to 365 days of Gregorian solar calendar. So the beginning of each lunar year go on shifting on solar calendar every year. It goes on receding until a full cycle is completed. After around every 19/20 years the beginning of solar and lunar calendar coincide with each other. Chinese festivals and religious ceremonies are determined as per Lunar calendar (354 days or as an average 29.5 days per Lunar month) but it exist within Solar Calendar of 365 days. So the dates of the festivals may vary from year to year. Year starts on new moon day. irrespective of date on lunar calendar, falling near to Vernal Commences (approaching vernal equinox) which is regarded to be falling on Feb 3-5, when Sun is transiting through Aquarius sign at 315 degree longitude. It is around 2 new moon after Winter solstice(Dec 21-22). Months start on new moon day and ends before next new moon day. The length of month varies from 29(short month) to 30 days (long month).
As discussed, Lunar year of 354 days (360 rotation of moon around the earth or on ecliptic) spans within Solar year of 365 days. The Gregorians Leap year concept of 366 days is not applied. In general there are 12 months in a year in both the cases. So the beginning of Lunar Year and Solar year varies from year to Year. But there is cycle of 19/20 years after which the beginning of the two may coincide. The issue of intercalation arises. That is to say after certain interval( 32/33 months or 2.6 years) one month extra is accumulated to cause a difference of 1 month between the beginnings of the two types of years. This month is called intercalary month. The Lunar year in which there is an intercalary month is called a leap year (as distinguished from Gregorian’s leap year of 366 days after every 4 years) having 13 Lunar months in the year, or say dropping one last lunar month from counting. But still, even after intercalation, the Lunar and solar calendar normally does not coincide unless a cycle of 19 years is completed. ((Actually intercalation also take into account 1 extra day of Gregorian calendar’s leap years having 366 days. So 1 intercalary month is accumulated more than half day( 2.6 years is around half of 4 years) before the actual one so that Lunar and Solar year may coincide. So even after removing one lunar month as intercalary month, the Solar and Lunar year normally do not coincide. But after a cycle of 19 years there comes a situation when the two go to coincide.))
In a cycle of 19 years there are 7 leap years. Remaining are called common years. In the cycle of 19 solar years the intercalary month may fall anytime in the solar year. But even this cycle of 19 years required an adjustment of one week for the beginning of two type of years to coincide. The Islamic calendar which has its origin in this Chinese calendar later on decided to go in favor of pure Lunar year without intercalation, in order to avoid inconvenience caused to pilgrims in Haj i.e. visit to Mecca. So beginning of the Lunar year goes on rotating around the Solar year in cyclic fashion.
There are two traditions regarding month nomenclature- 12 Climate Terms and 24 Solar Terms. Each Climate term is divided into 2 Solar Terms. Each Climate terms marks transit of Sun along ecliptic by 15 degree each. Those are enumerated as follows (Climate term followed by beginning of two Solar terms). We are avoiding mentioning Chinese equivalent of the Climate term.
Climate Term : Solar Term—————————–Solar Term
- Early Spring :Vernal Commences (Feb 3-5)–Vernal Showers (Feb 18-20)
- Mid Spring :Insects Waken (March 5-7)—-Vernal Equinox (March 21-22)
- Late Spring :Bright and Clear (April 4-6)—Corn Rain (April 19-21)
- Early Summer: Summer Commences (March 5-7)–Corn Forms (May 20-22)
- Mid Summer :Corn on Ear (June 5-7)–Summer Solstice (June 21-22)
- Late Summer : Moderate Heat (June 6-8)–Great Heat (June 22-24)
- Early Autumn:Autumn Commences (Aug 7-9)–End of Heat (Aug 22-24)
- Mid Autumn :White Dew (Sep 7-9)– Autumnal Equinox (Sep 22-24)
- Late Autumn :Cold Dew (Oct 8-9)– First Frost (Oct 23-24)
- Early Winter :Winter commences (Nov 7-8)–Light Snow (Nov 22-23)
- Mid Winter- :Heavy Snow (Dec 6-8)– Winter Solstice (Dec 21-23)
- Late Winter- :Moderate Cold(June 5-7) –Great Cold(June 20-21)
Months are also divided into 3 Xun(Chinese) each-Early(10 days) Xun, Mid(10 days) Xun and Late(9 to 10 days) Xun. Days begin at midnight and ends before next midnight but traditionally Sunrise is regarded to be beginning of day. Week as usually consists of 7 days and numbered as ordinal number 1,2..6, except Sunday.. In ancient time there were two systems of timing- Shi-Ke AND Geng-Dian. One day consisted of
1) 12 shi and 100 ke in Shi-KE system
2) 10 Geng and 60 Dian and 6000 fen in Geng-Dian system.
Presently this Time is scaled with hh:mm:ss.
In addition the system of Luni-solar calendar is integrated with three fundamentals namely Principle of Yin-Yang, Wu-Xing and Chinese astrology .
As per Principle of Wu-Xing there are five planets and hence 5 elements which rule over human destiny or character-Venus/Metal, Jupiter/Wood, Mercury/Water, Mars/Fire and Saturn/Earth. Each year is assigned a particular planet or the element. Accordingly a person’s character is adjudged.
Then as per principle of Yin-Yang, years are Yang(Like Male or Day) Year or Yin(Female or Night) Year, in order, after every 2 alternate years. This Yang- Yin concept is further integrated with Wu-Xing principle of 5 elements(changes) in the order as described above (Metal, Wood, Water, Fire, Earth ). (This is in keeping with Panchbhoot Tatav concept of Indian metaphysics. So the five elements correspond to the five primary type of consciousness determining one’s astrophysical being. That is why it is called Heavenly/Celestial stem.) So if first two years are Yang/Metal and Yin/Metal then third and fourth years are Yang/Wood and Yin/Wood respectively and so on. The counting may start from the beginning of the year (Lunar year of 354 days) ending with number 0(e.g. 1920) up to year ending with number 9(1929). It may also be said that if year ends with odd number (1,3…) then it is Yin otherwise Yang. So it goes to constitute a cycle of 10 years. This 10 years Cycle is said to go constitute a cycle of 10 Heavenly Stems.
Further as per Chinese astrology years are ruled by a succession of 12 animal signs namely-
Rat, Pig, Dog, Chicken(rooster), Monkey, Goat, Horse, Snake, Dragon, Rabbit, Tiger and Ox.(Rabbit is replaced with ‘cat’ in Vietnam)
(This has also something to do with rebirth cycle theory as enunciated by Lord Buddha. Actually these 12 animals are said to be rule over human psychology or guiding mode of pleasure & action irrespective of whichever might be one’s own apparent psychology or being. ). This 12 years cycle has been chosen in keeping with Jupiter’s one revolution around Sun or in Zodiac belt. It is around 11.86 years which has been rounded to 12 years. The 12 sign is said to cover a Zodiac belt of 28 constellations like 27 asterisms of Indian astrology. An animal sign is assigned to year, starting from one Yang Metal, in the order of the animal signs as described above. This cycle of 12 animals sign as assigned to 12 years in order is said to be a system of Earthly Branches. So overall it goes to constitute a cycle of 60 years (6 cycles of Heavenly elements(10*6)) OR 5 cycles of Earthly elements(12*5)) after which the cycle is repeated in exactly same fashion. Within each cycle of 60 years, each zodiac sign is associated with a series of 5 elements Yang OR 5 elements Yin in order. Present cycle is said to be starting from 1984 with Earthly Branch or Zodiac sign Rat and Heavenly Stem Yang Wood. This will come back again to the same position in the year 2044.
For illustration(keeping in mind all the principles as described above) a cycle of 60 years will go like that
Year ——————————-Heavenly stems ——-Earthly Branches
Feb 02 1984 to Jan 21 1985 – Yang Wood- Rat
Jan 22 1985 to Feb 08 1986- -Yin Wood – Ox
Feb 09 1986 to Jan 28 1987- Yang Fire— Tiger
Jan 29 1987 to Feb 16 1988- Yin Fire —- Rabbit
And so on up to
Feb 10 2043 to Jan 29 2044 – Yin Water ———— Pig
Further there are Stem Branches. Each row of Heavenly Stems and Earthly branch is jointly called a stem branch which further may explode into days in the two halves of each Climate term.
Japan AND Korea is also following Chinese Calendar with certain alteration/moderation.
Here follows a short note on measurable time as per the requirement of Calendar system.
Before we come to issue at hand it needs to be reminded that earth completes one rotation around its axis in 23 hours 56 minutes and 4 second. But it is also associated with orbital motion, motion in an orbit around sun; so that by the time earth has completed the rotation it has already moved 1 degree ahead on the orbit. So if earth is assumed to be static (Geocentric view) then it appears that Sun has moved back by the same amount. So earth has to rotate by around 1 degree more (making it total 361 degree) which takes 3 minutes 56 second time more, to see the rising Sun. This goes to make it apparently 24 hours for one complete rotation. This is with respect to Sun. So, overall, earth rotates by 1 degree in 4 minute (24*60/360) around its axis(though the rate of rotation may vary in 24 hours but the total time taken is always constant). The concept of our measurable time is associated with this 24 hours rotation of earth. There are two such concepts, Local mean time and Standard time. But if we go by a star at astronomical distance, which appears to be static as seen from earth in spite of earth’s orbital motion, then the rotation is completed in 23 hours 56 minute and 4 second. This duration is called sidereal day for the sidereal movement of earth. As we will see ahead there is concept of time associated with sidereal day as well. This is called star time or Sidereal Time.
We know that in keeping with the above mentioned concept of measurable time, world has been divided into 24 time zones each around 15 degree wide starting at Greenwich. Different parts of the word use its own time as per their longitude. This is called Local time. This ensures that whichever part of the world one is, it is always 12 ‘o’ clock noon when Sun is at overhead standard meridian that is directly overhead. The division of earth into longitudes is taken to be starting at Greenwich. So it is 0 degree (or 360 degree) longitude at Greenwich. Further it goes on increasing eastward. By each degree of change in longitude the time changes by 4 minute, ahead in eastward direction and behind in westward direction. We know that Christian/Gregorian date changes at 12 ‘o’ clock night. So if it is 12 ‘o’ clock night, 2 October at Greenwich then it is 12 hours & 4 minute night,2 October at 1 degree longitude, and so on increasing in eastward direction (in the order of 1,2,3 degrees….up to 180 degree longitude). At longitudes behind, westward, it will be 1 day behind, i.e. 1st October, again up to 180 degree longitude (in the order of 359,358,357 degrees…). Obviously at 180 degree longitude, passing through Pacific Ocean, a paradox would come into existence. If a person crosses this line from eastern part to western part he will have to set his clock one day behind. If the movement is in eastward direction then it has to be one day ahead. So this line is called International Date Line. As the earth rotates west to east around its axis the sun rises in east. The Sun rises earlier in eastern part (0 degree to 180 degree longitude) than in the western part of world (360 degree to 180 degree longitude).
So when time changes with longitude the question arises which of times should be followed. Each country has its own one more time zones which are used in different span of longitudes around a given longitude called standard meridian. USA has such 15 time zones. UK has 13 time zones. Canada has 9 time zones. Rest most of the countries has one time zone of their own. India has its time zone centered at 82.5 degree as standard meridian. So whatever time it comes to be at 82.5 degree longitude it is taken to be Standard time for whole of the India as per the Indian clock. This is called Indian Standard time. But prior to this several local times zones were under use which is practically of no significance now. But actual time or Local time at different place or at different longitude is different. We know that if it is morning 6 ‘o’ clock at Delhi and if Sun has risen over there, then in Punjab (west to Delhi) it may be dark. For each degree change in longitude actual time is reduced in westward longitude by 4 minute and increases by same amount in eastward longitude. In Astrology we need to convert Standard Time of the Zone into Local time. IST runs 5 hours 30 minute ahead of Greenwich Time (82.5*4=330 minute=5 hours 30 minute). So if it is 11 ‘o’ clock night i.e. 23 hours IST, then at Shimla (at longitude 77 degree & 10 minute) Local time will be (82.5-77.17=5.33) * 4 =21.32 minute less. So Local time (as distinguished from ‘clock time’ or ‘standard time’) at Shimla will be 22 hours 28 minutes night. At Greenwich it will be 17 hours and 30 minute evening at that time. It is 12 ‘o’ clock noon at international date line when it is 12 ‘o’ clock night at Greenwich and so on.
Sidereal time is used in Astrology to show the position of planets in any part of the world which is same for all places. As we have discussed that sidereal day is of span 23 hours 56 minutes and 4 seconds. The remaining part of 24 hours (i.e. 3 minute and 56 second or around 4 minutes) is called sidereal time. The earth is assumed to start its journey on vernal equinox day at 12 noon when Sun in its northward journey (geocentric view) in ecliptic crosses the first point , i.e. 0 degree, of tropical Aries sign( which as per sidereal astrology is around 5 degree Pisces presently). This is the point where earth’s celestial equator and ecliptic crosses each other while Sun is in its northward journey. (This point is ever shifting in clockwise direction of zodiacal belt because of earth’s processional motion.) At this point of time sidereal time at Greenwich is taken to be 0 hours. Next day by 12 ‘o’ clock noon sidereal time increases by about, but less than, 4 minutes and so on, so that by next vernal equinox day (365/366 days) it comes to be 24 hours, and the journey starts again. Sidereal times at other places are subjected to two corrections (properly three) with reference to Greenwich sidereal time at 12 noon LMT. First it is the longitudinal correction and second is the correction for time ahead or behind 12 noon. Almanac may show sidereal time as per other standard longitude of their own and other LMT, say 5.30 ‘o’ clock morning, which has to be also subjected to same corrections but with reference to this standard longitude and time. For 360 degree change of longitude, or rotation of earth, around 4 minutes correction is needed. So for per degree change of longitude, from reference line, 2/3 seconds (360/4*60) corrections in reference sidereal time is required. Further for time correction we have to take difference between Local mean time and the reference LMT of almanac. This difference of time causes a further change in sidereal time by a rate of 10 seconds per hour(4/24*60). If In both corrections it may be increment or reduction in the reference sidereal time of almanac. If given longitude is eastward to reference longitude then it is a case of addition otherwise it is deduction. Similarly if the given LMT is more than reference time then it is case of addition otherwise deduction. In astrology a further correction for year, arising on account of variation in rate of precessional motion of earth, may be required.
In equatorial coordinate system( as used for any object on Celestial sphere) Local sidereal time of a star in the sky is also defined as
Local Sidereal time=Right ascension (given in hour/minute) + Local hour angle.
It is beyond the scope of this article to explain it. Please look at http://books.google.com/?id=s_o4AAAAMAAJ