Patterns of Moon, Patterns of Sun
The Hijri Calendar
In AD 638, six years after the death of the Prophet Muhammad, Islam's second caliph Umar recognized the necessity of a calendar to govern the affairs of the Muslims. This was first of all a practical matter. Correspondence with military and civilian officials in the newly conquered lands had to be dated. But Persia used a different calendar from Syria, where the caliphate was based; Egypt used yet another. Each of these calendars had a different starting point, or epoch. The Sasanids, the ruling dynasty of Persia, used June 16, AD 632, the date of the accession of the last Sasanid monarch, Yazdagird III. Syria, which until the Muslim conquest was part of the Byzantine Empire, used a form of the Roman "Julian" calendar, with an epoch of October 1, 312 BC . Egypt used the Coptic calendar, with an epoch of August 29, AD 284. Although all were solar, and hence geared to the seasons and containing 365 days, each also had a different system for periodically adding days to compensate for the fact that the true length of the solar year is not 365 but 365.2422 days.
In pre-Islamic Arabia, various other systems of measuring time had been used. In South Arabia, some calendars apparently were lunar, while others were lunisolar, using months based on the phases of the moon but intercalating days outside the lunar cycle to synchronize the calendar with the seasons. On the eve of Islam, the Himyarites appear to have used a calendar based on the Julian form, but with an epoch of 110 BC. In central Arabia, the course of the year was charted by the position of the stars relative to the horizon at sunset or sunrise, dividing the ecliptic into 28 equal parts corresponding to the location of the moon on each successive night of the month. The names of the months in that calendar have continued in the Islamic calendar to this day and would seem to indicate that, before Islam, some sort of lunisolar calendar was in use, though it is not known to have had an epoch other than memorable local events.
There were two other reasons Umar rejected existing solar calendars. The Quran, in Chapter 10, Verse 5, states that time should be reckoned by the moon. Not only that, calendars used by the Persians, Syrians and Egyptians were identified with other religions and cultures. He therefore decided to create a calendar specifically for the Muslim community. It would be lunar, and it would have 12 months, each with 29 or 30 days.
This gives the lunar year 354 days, 11 days fewer than the solar year. Umar chose as the epoch for the new Muslim calendar the hijrah, the emigration of the Prophet Muhammad and 70 Muslims from Makkah to Madinah, where Muslims first attained religious and political autonomy. The hijrah thus occurred on 1 Muharram 1 according to the Islamic calendar, which was named "hijri" after its epoch. (This date corresponds to July 16, AD 622 on the Gregorian calendar.) Today in the West, it is customary, when writing hijri dates, to use the abbreviation ah, which stands for the Latin anno hegirae, "year of the hijrah."
Because the Islamic lunar calendar is 11 days shorter than the solar, itis therefore not synchronized to the seasons. Its festivals, which fall on the same days of the same lunar months each year, make the round of the seasons every 33 solar years. This 11-day difference between the lunar and the solar year accounts for the difficulty of converting dates from one system to the other.
The Gregorian Calendar
The early calendar of the Roman Empire was lunisolar, containing 355 days divided into 12 months beginning on January 1. To keep it more or less in accord with the actual solar year, a month was added every two years. The system for doing so was complex, and cumulative errors gradually misaligned it with the seasons. By 46 BC , it was some three months out of alignment, and Julius Caesar oversaw its reform. Consulting Greek astronomers in Alexandria, he created a solar calendar in which one day was added to February every fourth year, effectively compensating for the solar year's length of 365.2422 days. This Julian calendar was used throughout Europe until AD 1582.
In the Middle Ages, the Christian liturgical calendar was grafted onto the Julian one, and the computation of lunar festivals like Easter, which falls on the first Sunday after the first full moon after the spring equinox, exercised some of the best minds in Christendom. The use of the epoch AD 1 dates from the sixth century, but did not become common until the 10th. Because the zero had not yet reached the West from Islamic lands, a year was lost between 1 BC and AD 1.
The Julian year was nonetheless 11 minutes and 14 seconds too long. By the early 16th century, due to the accumulated error, the spring equinox was falling on March 11 rather than where it should, on March 21. Copernicus, Christophorus Clavius and the physician Aloysius Lilius provided the calculations, and in 1582 Pope Gregory XIII ordered that Thursday, October 4, 1582 would be followed by Friday, October 15, 1582. Most Catholic countries accepted the new "Gregorian" calendar, but it was not adopted in England and the Americas until the 18th century. Its use is now almost universal worldwide. The Gregorian year is nonetheless 25.96 seconds ahead of the solar year, whichby the year 4909 will add up to an extra day.
Historian Paul Lunde (firstname.lastname@example.org) specializes in Islamic history and literature. His most recent book is Islam: Culture, Faith and History (2001, Dorling Kindersley).
This article has been reprinted with permission from Saudi Aramco World Magazine (November/December 2005).
Photo Attribution: http://commons.wikimedia.org/wiki/File:Lunar_eclipse01.JPEG
"Kulingana na kalenda ya Hijri, mwaka 638 KK, baada ya kifo cha Mtume Muhammad, Khalifa wa pili wa Uislamu, Umar, alitambua umuhimu wa kalenda ya kuongoza mambo ya Waislamu.""" Hili lilikuwa jambo la vitendo kwanza kabisa. Barua-mawasiliano na maofisa wa kijeshi na raia katika nchi zilizokuwa zimeshindwa hivi karibuni zilipaswa kuandikwa tarehe. Lakini Uajemi walitumia kalenda tofauti na ile ya Siria, ambako ufalme wa Uislamu ulikuwa umekua; Misri ilitumia kalenda nyingine. Kila moja ya kalenda hizo ilikuwa na mwanzo tofauti, au enzi tofauti. Sassanids, nasaba ya utawala wa Uajemi, ilitumia tarehe 16 Juni 632, tarehe ya kuingia kwa mfalme wa mwisho wa Sassanid, Yazdagirid III. "Syria, ambayo hadi ushindi wa Kiislamu ilikuwa sehemu ya Milki ya Byzantium, ilitumia aina ya kalenda ya Kirumi ya ""Julian,"" na enzi ya Oktoba 1, 312 KK." Misri ilitumia kalenda ya Coptic, na tarehe ya Agosti 29, 284 W.K. Ingawa kila mwaka ulikuwa na siku 365 za jua, kila mwaka ulikuwa na siku 365 za jua, na kila mwaka ulikuwa na siku 365 za jua, lakini kwa sababu ya muda wa siku 365 na siku 365.242 zilikuwa na siku 365.242 za jua. Katika Arabia kabla ya Uislamu, mifumo mingine mbalimbali ya kupima wakati ilikuwa imetumiwa. Katika Arabia Kusini, baadhi ya kalenda zilikuwa za mwezi, wakati nyingine zilikuwa za mwezi na jua, zikitumia miezi kulingana na awamu za mwezi lakini zikijipanga siku nje ya mzunguko wa mwezi ili kuunganisha kalenda na misimu. Katika kipindi cha kabla ya Uislamu, Wa-Himyarite walitumia kalenda ya Julian, lakini kwa kipindi cha mwaka 110 KK. Katika Arabia ya Kati, mwendo wa mwaka ulifunuliwa kwa nafasi ya nyota ikilinganishwa na upeo wa macho wakati wa machweo au kuchomoza kwa jua, ikigawanya ecliptic katika sehemu 28 sawa zinazolingana na eneo la mwezi katika kila usiku wa mwezi. Majina ya miezi katika kalenda hiyo yameendelea katika kalenda ya Kiislamu hadi leo na inaonekana kuonyesha kwamba, kabla ya Uislamu, aina fulani ya kalenda ya lunisolar ilikuwa ikitumiwa, ingawa haijulikani kuwa na enzi nyingine isipokuwa matukio ya kukumbukwa ya ndani. Kulikuwa na sababu nyingine mbili ambazo zilifanya Umar akatae kalenda za jua zilizokuwapo. "Koran inasema katika sura ya 10 aya ya 5 ""Na wakati unapaswa kuhesabiwa kwa mwezi.""" Kwa sababu hiyo, kalenda za Waajemi, Wasiria, na Wamisri zilikuwa na uhusiano wa karibu na dini na tamaduni nyingine. Kwa hiyo aliamua kutengeneza kalenda hasa kwa ajili ya jamii ya Waislamu. Mwezi huo ulikuwa na miezi 12 kila mwezi ikiwa na siku 29 au 30. Mwaka wa mwezi una siku 354, siku 11 chini ya mwaka wa jua. Umar alichagua kama kipindi cha kalenda mpya ya Kiislamu Hijrah, uhamiaji wa Mtume Muhammad na Waislamu 70 kutoka Makkah hadi Madina, ambapo Waislamu walipata uhuru wa kidini na kisiasa. "Hijrah ilifanyika tarehe 1 Muharram 1 kulingana na kalenda ya Kiislamu, ambayo iliitwa ""Hijri"" baada ya enzi yake." Tarehe hiyo ni Julai 16, 622 KK kulingana na kalenda ya Gregorian. "Kama ilivyo kwa Kiingereza, tarehe ya Hijri huandikwa kwa kutumia kifupi cha ""AH"" (Anno Hegirae) - ""Mwaka wa Hijri.""" Kalenda ya mwezi wa Kiislamu ni fupi kwa siku 11 kuliko kalenda ya jua, na kwa hivyo haifanyi kazi kwa msimu. Sherehe zake, ambazo hufanyika siku zilezile za mwezi mmoja kila mwaka, hufanya mzunguko wa majira kila baada ya miaka 33 ya jua. Tofauti ya siku 11 kati ya mwaka wa mwezi na mwaka wa jua ni moja ya sababu za kutofautisha tarehe kati ya mfumo mmoja na mwingine. Kalenda ya Gregorian ilikuwa kalenda ya kwanza ya Milki ya Roma, na ilikuwa na siku 355 zilizogawanywa katika miezi 12 kuanzia Januari 1. Ili ifanane zaidi au chini na mwaka halisi wa jua, mwezi uliongezwa kila baada ya miaka miwili. Mfumo wa kufanya hivyo ulikuwa tata, na makosa yaliyokusanywa polepole yaliufanya usifanye kazi kulingana na majira. Mwaka 46 KK, wakati wa utawala wa Julius Kaisari, serikali ya Roma ilibadilika. Alipowaomba wataalamu wa nyota wa Kigiriki huko Aleksandria, aliunda kalenda ya jua ambayo iliongeza siku moja kwa Februari kila baada ya miaka minne, na hivyo kulipa fidia kwa urefu wa mwaka wa jua wa siku 365,242. Kalenda ya Julian ilitumika katika Ulaya yote hadi mwaka 1582. Katika enzi za kati, kalenda ya Kikristo ya ibada ilibadilishwa na kalenda ya Julian, na kuhesabu sikukuu za mwezi kama vile Pasaka, ambayo huanguka Jumapili ya kwanza baada ya mwezi kamili baada ya equinox ya spring, ilifanya baadhi ya akili bora katika Ukristo. "Utumizi wa ""Epoche AD 1"" ulianza katika karne ya sita, lakini haukuanza kuwa wa kawaida hadi karne ya kumi." Kwa sababu sifuri haikuwa imefika Magharibi kutoka nchi za Kiislamu, mwaka mmoja ulipotea kati ya mwaka 1 KK na mwaka 1 KK. Mwaka wa Julian ulikuwa na urefu wa dakika 11 na sekunde 14. Katika karne ya 16 na 20, kwa sababu ya makosa yaliyokusanywa, equinox ya spring ilikuwa ikianguka tarehe 11 Machi badala ya mahali inapaswa kuwa, tarehe 21 Machi. Copernicus, Christopher Clavius na Aloysius Lilius walifanya hesabu hizo, na mwaka wa 1582 Papa Gregory wa 13 aliamuru kwamba siku ya Alhamisi, Oktoba 4, 1582 ifuatiwe na Ijumaa, Oktoba 15, 1582. "Kama ilivyoelezwa hapo juu, kalenda ya ""Gregori"" ilitumiwa na Wakatoliki wengi, lakini ilichukuliwa na Wakatoliki wengi katika karne ya 18 na baadaye katika karne ya 19." Sasa inatumiwa karibu ulimwenguni pote. Mwaka wa Gregorian una sekunde 25.96 mbele ya mwaka wa jua, na mwaka wa 4909 utaongeza siku moja zaidi. Mwanahistoria Paul Lunde (jina la kwanza.jina la mwisho@mfano.org) ni mtaalamu wa historia na fasihi ya Kiislamu. Kitabu chake cha hivi karibuni ni Uislamu: Utamaduni, Imani na Historia (2001, Dorling Kindersley). Makala hii imechapishwa tena kwa ruhusa ya Saudi Aramco World Magazine (Novemba-Desemba 2005). Picha: http: www.community.org wiki wiki wiki_lunar eclipse_jpg