Month - Wikipedia Month A month is a unit of time, used with calendars, which is approximately as long as a natural period related to the motion of the Moon ; month and Moon are cognates. The traditional concept arose with the cycle of moon phases ; such months ( lunations ) are synodic months and last approximately 29.53 days. From excavated tally sticks, researchers have deduced that people counted days in relation to the Moon 's phases as early as the Paleolithic age. Synodic months, based on the Moon 's orbital period with respect to the Earth - Sun line, are still the basis of many calendars today, and are used to divide the year. Contents 1 Types of months in astronomy 2 Calendrical consequences 3 Months in various calendars 3.1 Beginning of the lunar month 3.2 Julian and Gregorian calendars 3.2. 1 Calends, nones, and ides 3.3 Hebrew calendar 3.4 Islamic calendar 3.5 Arabic calendar 3.6 Hindu calendar 3.7 Bahá'í calendar 3.8 Iranian calendars ( Persian calendars ) 3.9 Reformed Bengali calendar 3.10 Nanakshahi calendar 3.11 Khmer calendar 3.12 Thai calendar 3.13 Tongan calendar 3.14 Kollam era ( Malayalam ) calendar 3.15 Sinhala calendar 3.16 Germanic calendar 3.17 Old Georgian calendar 3.18 Old Swedish calendar 3.19 Old English calendar 3.20 Old Hungarian calendar 3.21 Old Egyptian calendar 3.22 Nisga'a calendar 3.23 French Republican calendar 4 Adhik Maas 5 See also 6 References Types of months in astronomy Main article : Lunar month The following types of months are mainly of significance in astronomy, most of them ( but not the distinction between sidereal and tropical months ) first recognized in Babylonian lunar astronomy. The sidereal month is defined as the Moon 's orbital period in a non-rotating frame of reference ( which on average is equal to its rotation period in the same frame ). It is about 27.32166 days ( 27 days, 7 hours, 43 minutes, 11.6 seconds ). It is closely equal to the time it takes the Moon to pass twice a `` fixed '' star ( different stars give different results because all have a very small proper motion and are not really fixed in position ). A synodic month is the most familiar lunar cycle, defined as the time interval between two consecutive occurrences of a particular phase ( such as new moon or full moon ) as seen by an observer on Earth. The mean length of the synodic month is 29.53059 days ( 29 days, 12 hours, 44 minutes, 2.8 seconds ). Due to the eccentricity of the lunar orbit around Earth ( and to a lesser degree, the Earth 's elliptical orbit around the Sun ), the length of a synodic month can vary by up to seven hours. The tropical month is the average time for the Moon to pass twice through the same equinox point of the sky. It is 27.32158 days, very slightly shorter than the sidereal month ( 27.32166 ) days, because of precession of the equinoxes. An anomalistic month is the average time the Moon takes to go from perigee to perigee - the point in the Moon 's orbit when it is closest to Earth. An anomalistic month is about 27.55455 days on average. The draconic month, draconitic month, or nodal month is the period in which the Moon returns to the same node of its orbit ; the nodes are the two points where the Moon 's orbit crosses the plane of the Earth 's orbit. Its duration is about 27.21222 days on average. A synodic month is longer than a sidereal month because the Earth - Moon system is orbiting the Sun in the same direction as the Moon is orbiting the Earth. The Sun moves eastward with respect to the stars ( as does the Moon ) and it takes about 2.2 days longer for the Moon to return to the same apparent position with respect to the Sun. An anomalistic month is longer than a sidereal month because the perigee moves in the same direction as the Moon is orbiting the Earth, one revolution in nine years. Therefore, the Moon takes a little longer to return to perigee than to return to the same star. A draconic month is shorter than a sidereal month because the nodes move in the opposite direction as the Moon is orbiting the Earth, one revolution in 18.6 years. Therefore, the Moon returns to the same node slightly earlier than it returns to the same star. Calendrical consequences For more details on this topic, see lunar calendar and lunisolar calendar. At the simplest level, most well - known lunar calendars are based on the initial approximation that 2 lunations last 59 days : a 30 - day full month followed by a 29 - day hollow month -- but this is only roughly accurate, and eventually needs correction by using larger cycles, or the equivalent of leap days. Additionally, the synodic month does not fit easily into the year, which makes accurate, rule - based lunisolar calendars complicated. The most common solution to this problem is the Metonic cycle, which takes advantage of the fact that 235 lunations are approximately 19 tropical years ( which add up to not quite 6940 days ). However, a Metonic calendar will drift against the seasons by about 1 day every 200 years. Metonic calendars include the calendar used in the Antikythera Mechanism about 2000 years ago, and the Hebrew calendar. The complexity required in an accurate lunisolar calendar may explain why solar calendars ( which have months which no longer relate to the phase of the Moon, but are based only on the motion of the Sun relative to the equinoxes and solstices ) have generally replaced lunar calendars for civil use in most societies. Months in various calendars Beginning of the lunar month The Hellenic calendars, the Hebrew Lunisolar calendar and the Islamic Lunar calendar started the month with the first appearance of the thin crescent of the new moon. However, the motion of the Moon in its orbit is very complicated and its period is not constant. The date and time of this actual observation depends on the exact geographical longitude as well as latitude, atmospheric conditions, the visual acuity of the observers, etc. Therefore, the beginning and lengths of months defined by observation can not be accurately predicted. While some like the Jewish Karaites still rely on actual moon observations, most people use the Gregorian solar calendar. Pingelapese, a language from Micronesia, also uses a lunar calendar. There are 12 months associated with their calendar. The moon first appears in March, they name this month Kahlek. This system has been used for hundreds of years and throughout many generations. This calendar is cyclical and relies on the position and shape of the moon. Julian and Gregorian calendars The Gregorian calendar, like the Julian calendar before it, has twelve months : Chronology Alphabetic Days January 31 days February 28 days, 29 in leap years March 31 days April 30 days 5 May 31 days 6 June 30 days 7 July 31 days 8 August 31 days 9 September 30 days 10 October 31 days 11 November 30 days 12 December 31 days One of Wikipedia 's sister projects, Wiktionary, provides translations of each of the Gregorian / Julian calendar months into a dozen or more languages. Month - by - month links are provided here : January, February, March, April, May, June, July, August, September, October, November, December. On top of the knuckles ( yellow ) : 31 days Between the knuckles ( blue ) : 30 days February ( red ) has 28 or 29 days. The white keys of the musical keyboard correlate to months with 31 days. ( ' F ' correlates to January. ) The mean month length of the Gregorian calendar is 30.436875 days. Months existing in the Roman calendar in the past include : the mensis intercalaris, an occasional month after February to realign the calendar. Quintilis, renamed to July in honour of Julius Caesar. Sextilis, renamed to August in honour of Augustus. The famous mnemonic Thirty days hath September is the most common way of teaching the lengths of the months in the English - speaking world. Also, note that any five consecutive months ( not including February ) contain 153 days. The knuckles of the four fingers of one 's hand and the spaces between them can be used to remember the lengths of the months. By making a fist, each month will be listed as one proceeds across the hand. All months landing on a knuckle are 31 days long and those landing between them are not. When the knuckle of the index finger is reached ( July ), go back to the first knuckle ( or over to the first knuckle on the other fist, held next to the first ) and continue with August. This physical mnemonic has been taught to primary school students for many decades. This cyclical pattern of month lengths matches the musical keyboard alternation of white and black keys ( with the note ' F ' correlating to the month of January ). Calends, nones, and ides The ides occur on the thirteenth day in eight of the months, but in March, May, July, and October, they occur on the fifteenth. The nones always occur 8 days ( one Roman week ) before the ides, i.e., on the fifth or the seventh. The calends are always the first day of the month, and before Julius Caesar 's reform fell sixteen days ( two Roman weeks ) after the ides ( except the ides of February and the intercalary month ). Hebrew calendar The Hebrew calendar has 12 or 13 months. Nisan, 30 days ניסן Iyar, 30 days אייר Sivan, 30 days סיון Tammuz, 29 days תמוז Av, 30 days אב Elul, 29 days אלול Tishri, 30 days תשרי Marcheshvan, 29 / 30 days מַרְחֶשְׁוָן Kislev, 30 / 29 days כסלו Tevet, 29 days טבת Shevat, 30 days שבט Adar 1, 30 days, intercalary month אדר א Adar 2, 29 days אדר ב Adar 1 is only added 7 times in 19 years. In ordinary years, Adar 2 is simply called Adar. Islamic calendar There are also twelve months in the Islamic calendar. They are named as follows : Muharram ( Restricted / sacred ) محرّم Safar ( Empty / Yellow ) صفر Rabī ' al - Awwal / Rabi ' I ( First Spring ) ربيع الأول Rabī ' ath - Thānī / Rabi ` al - Aakhir / Rabi ' II ( Second spring or Last spring ) ربيع الآخر أو ربيع الثاني Jumada al - Awwal / Jumaada I ( First Freeze ) جمادى الأول Jumada ath - Thānī or Jumādā al - Thānī / Jumādā II ( Second Freeze or Last Freeze ) جمادى الآخر أو جمادى الثاني Rajab ( To Respect ) رجب Sha'bān ( To Spread and Distribute ) شعبان Ramadān ( Parched Thirst ) رمضان Shawwāl ( To Be Light and Vigorous ) شوّال Dhu al - Qi'dah ( The Master of Truce ) ذو القعدة Dhu al - Hijjah ( The Possessor of Hajj ) ذو الحجة See Islamic calendar for more information on the Islamic calendar. Arabic calendar Main article : Arabic names of calendar months Gregorian month Arabic month January يناير كانون الثاني Kanun Al - Thani February فبراير شباط Shebat March مارس اذار Adhar April ابريل نيسان Nisan May مايو أيّار Ayyar June يونيو حزيران Ḩazayran July يوليو تمّوز Tammuz August أغسطس اَب ʕAb September سبتمبر أيلول Aylul October أكتوبر تشرين الأول Tishrin Al - Awwal November نوفمبر تشرين الثاني Tishrin Al - Thani December ديسمبر كانون الأول Kanun Al - Awwal Hindu calendar The Hindu calendar has various systems of naming the months. The months in the lunar calendar are : Sanskrit name Tamil name Telugu name Nepali name Caitra ( चैत्र ) Chitirai ( சித்திரை ) Chaithramu ( చైత్రము ) Chaitra ( चैत्र / चैत ) Vaiśākha ( वैशाख ) Vaikasi ( வைகாசி ) Vaisaakhamu ( వైశాఖము ) Baisakh ( बैशाख ) Jyeṣṭha ( ज्येष्ठ ) Aani ( ஆனி ) Jyeshttamu ( జ్యేష్ఠము ) Jesth ( जेष्ठ / जेठ ) Ashadha ( आषाढ ) Aadi ( ஆடி ) Aashaadhamu ( ఆషాఢము ) Aasad ( आषाढ / असार ) 5 Śrāvaṇa ( श्रावण ) Aavani ( ஆவணி ) Sraavanamu ( శ్రావణము ) Srawan ( श्रावण / साउन ) 6 Bhadrapada ( भाद्रपद ) Purratasi ( புரட்டாசி ) Bhaadhrapadamu ( భాద్రపదము ) Bhadau ( भाद्र भदौ ) 7 Āśvina ( अश्विन ) Aiypasi ( ஐப்பசி ) Aasveeyujamu ( ఆశ్వయుజము ) Asoj ( आश्विन / असोज ) 8 Kārtika ( कार्तिक ) Kaarthigai ( கார்த்திகை ) Kaarthikamu ( కార్తీకము ) Kartik ( कार्तिक ) 9 Mārgaśīrṣa ( मार्गशीर्ष ) Maargazhi ( மார்கழி ) Maargaseershamu ( మార్గశిరము ) Mangsir ( मार्ग / मंसिर ) 10 Pauṣa ( पौष ) Thai ( தை ) Pushyamu ( పుష్యము ) Push ( पौष / पुष / पूस ) 11 Māgha ( माघ ) Maasi ( மாசி ) Maaghamu ( మాఘము ) Magh ( माघ ) 12 Phālguna ( फाल्गुन ) Panguni ( பங்குனி ) Phaalgunamu ( ఫాల్గుణము ) Falgun ( फाल्गुन / फागुन ) These are also the names used in the Indian national calendar for the newly redefined months. Purushottam Maas or Adhik Maas ( translit. adhika = ' extra ', māsa = ' month ' ) is an extra month in the Hindu calendar that is inserted to keep the lunar and solar calendars aligned. `` Purushottam '' is an epithet of Vishnu, to whom the month is dedicated. The names in the solar calendar are just the names of the zodiac sign in which the sun travels. They are Mesha Vrishabha Mithuna Kataka Simha Kanyaa Tulaa Vrishcika Dhanus Makara Kumbha Miina Bahá'í calendar The Bahá'í calendar is the calendar used by the Bahá'í Faith. It is a solar calendar with regular years of 365 days, and leap years of 366 days. Years are composed of 19 months of 19 days each ( 361 days ), plus an extra period of `` Intercalary Days '' ( 4 in regular and 5 in leap years ). The months are named after the attributes of God. Days of the year begin and end at sundown. Iranian calendars ( Persian calendars ) The Iranian / Persian calendar, currently used in Iran and Afghanistan, also has 12 months. The Persian names are included in the parentheses. It begins on the northern Spring equinox. Farvardin ( 31 days, فروردین ) Ordibehesht ( 31 days, اردیبهشت ) Khordad ( 31 days, خرداد ) Tir ( 31 days, تیر ) Mordad ( 31 days, مرداد ) Shahrivar ( 31 days, شهریور ) Mehr ( 30 days, مهر ) Aban ( 30 days, آبان ) Azar ( 30 days, آذر ) Dey ( 30 days, دی ) Bahman ( 30 days, بهمن ) Esfand ( 29 days - 30 days in leap year, اسفند ) Reformed bengali calendar The Bangla calendar, used in Bangladesh, follows solar months and it has six seasons. The months and seasons in the calendar are : No. Name Bengali season Days Julian months Boishakh ( বৈশাখ ) Grishmo ( গ্রীষ্ম ) 31 14 April - May Joishtho ( জ্যৈষ্ঠ ) Grishmo ( গ্রীষ্ম ) 31 May - June Asharh ( আষাঢ় ) Borsha ( বর্ষা ) 31 June - July Shrabon ( শ্রাবণ ) Borsha ( বর্ষা ) 31 July - August 5 Bhadro ( ভাদ্র ) Shorot ( শরৎ ) 31 August - September 6 Aashin ( আশ্বিন ) Shorot ( শরৎ ) 30 September - October 7 Kartik ( কার্তিক ) Hemonto ( হেমন্ত ) 30 October - November 8 Ogrohayon ( অগ্রহায়ণ ) Hemonto ( হেমন্ত ) 30 November - December 9 Poush ( পৌষ ) Sheet ( শীত ) 30 December - January 10 Magh ( মাঘ ) Sheet ( শীত ) 30 January - February 11 Falgun ( ফাল্গুন ) Boshonto ( বসন্ত ) 30 ( 31 in leap years ) February - March 12 Choitro ( চৈত্র ) Boshonto ( বসন্ত ) 30 March - April Nanakshahi calendar The months in the Nanakshahi calendar are : No. Name Punjabi Days Julian months Chet ਚੇਤ 31 14 March -- 13 April Vaisakh ਵੈਸਾਖ 31 14 April -- 14 May Jeth ਜੇਠ 31 15 May -- 14 June Harh ਹਾੜ 31 15 June -- 15 July 5 Sawan ਸਾਵਣ 31 16 July -- 15 August 6 Bhadon ਭਾਦੋਂ 30 16 August -- 14 September 7 Assu ਅੱਸੂ 30 15 September -- 14 October 8 Katak ਕੱਤਕ 30 15 October -- 13 November 9 Maghar ਮੱਘਰ 30 14 November -- 13 December 10 Poh ਪੋਹ 30 14 December -- 12 January 11 Magh ਮਾਘ 30 13 January -- 11 February 12 Phagun ਫੱਗਣ 30 / 31 12 February -- 13 March Khmer calendar Like the Hindu calendar, the Khmer calendar consists of both a lunar calendar and a solar calendar. The Khmer solar calendar is used more commonly than the lunar calendar. There are 12 months and the numbers of days follow the Julian and Gregorian calendar. Khmer name Transliteration Julian and Gregorian name មករា Makara January កម្ភៈ Kompeak February មិនា or មីនា Mik Nea or Me Na March មេសា Mesa April 5 ឧសភា Uk Sak Phea May 6 មិថុនា Mik Thok Na June 7 កក្កដា Kak Ka Da July 8 សីហា Seiha August 9 កញ្ញា Kagna September 10 តុលា Tola October 11 វិច្ឆិកា Vicheka November 12 ធ្នូ Thnu December The Khmer lunar calendar contains 12 months ; however, the eighth month is repeated ( as a `` leap - month '' ) every two or three years, making 13 months instead of 12. មិគសិរ បុស្ស មាឃ ផល្គុន ចេត្រ វិសាខ / ពិសាខ ជេស្ឋ ឤសាឍ, or in the case of a year with a leap - month : បឋមសាឍ ទុតិយាសាឍ ស្រាពណ៍ ភទ្របទ អស្សុជ កត្តិក Thai calendar Main articles : Thai solar calendar and Thai lunar calendar English name Thai name Abbr. Transcription Sanskrit word Zodiac sign January มกราคม ม. ค. mokarakhom mokara `` sea - monster '' Capricorn February กุมภาพันธ์ ก. พ. kumphaphan kumbha `` pitcher, water - pot '' Aquarius March มีนาคม มี. ค. minakhom mīna `` ( a specific kind of ) fish '' Pisces April เมษายน เม. ย. mesayon meṣa `` ram '' Aries May พฤษภาคม พ. ค. phruetsaphakhom vṛṣabha `` bull '' Taurus June มิถุนายน มิ. ย. mithunayon mithuna `` a pair '' Gemini July กรกฎาคม ก. ค. karakadakhom karkaṭa `` crab '' Cancer August สิงหาคม ส. ค. singhakhom siṃha `` lion '' Leo September กันยายน ก. ย. kanyayon kanyā `` girl '' Virgo October ตุลาคม ต. ค. tulakhom tulā `` balance '' Libra November พฤศจิกายน พ. ย. phruetsachikayon vṛścika `` scorpion '' Scorpio December ธันวาคม ธ. ค. thanwakhom dhanu `` bow, arc '' Sagittarius Tongan calendar The Tongan calendar is based on the cycles of the moon around the earth in one year. The months are : Liha Mu'a Liha Mui Vai Mu'a Vai Mui Faka'afu Mo'ui Faka'afu Mate Hilinga Kelekele Hilinga Mea'a ' Ao'ao Fu'ufu'unekinanga ' Uluenga Tanumanga ' O'oamofanongo Kollam era ( Malayalam ) calendar Main article : Kollam era Malayalam name Transliteration Concurrent Gregorian months Sanskrit word and meaning Zodiac sign ചിങ്ങം chi - ngnga - m August -- September simha `` lion '' Leo കന്നി ka - nni September -- October kanyā `` girl '' Virgo തുലാം thu - lā - m October -- November tulā `` balance '' Libra വൃശ്ചികം vRSh - chi - ka - m November -- December vṛścika `` scorpion '' Scorpio ധനു dha - nu December -- January dhanu `` bow, arc '' Sagittarius മകരം ma - ka - ra - m January -- February mokara `` sea - monster '' Capricorn കുംഭം kum - bha - m February -- March kumbha `` pitcher, water - pot '' Aquarius മീനം mee - na - m March -- April mīna `` ( a specific kind of ) fish '' Pisces മേടം mE - Da - m April -- May meṣa `` ram '' Aries ഇടവം i - Ta - va - m May - June vṛṣabha `` bull '' Taurus മിഥുനം mi - thu - na - m June -- July mithuna `` a pair '' Gemini കർക്കടകം kar - kka - Ta - ka - m July -- August karkaṭa `` crab '' Cancer Sinhala calendar The Sinhala calendar is the Buddhist calendar in Sri Lanka with Sinhala names. Each full moon Poya day marks the start of a Buddhist lunar month. The first month is Vesak. Duruthu ( දුරුතු ) Navam ( නවම් ) Mædin ( මැදින් ) Bak ( බක් ) Vesak ( වෙසක් ) Poson ( පොසොන් ) Æsala ( ඇසල ) Nikini ( නිකිණි ) Binara ( බිනර ) Vap ( වප් ) Il ( iL ) ( ඉල් ) Unduvap ( උඳුවප් ) Germanic calendar Main article : Germanic calendar The old Icelandic calendar is not in official use anymore, but some Icelandic holidays and annual feasts are still calculated from it. It has 12 months, broken down into two groups of six often termed `` winter months '' and `` summer months ''. The calendar is peculiar in that the months always start on the same weekday rather than on the same date. Hence Þorri always starts on a Friday sometime between January 22 and January 28 ( Old style : January 9 to January 15 ), Góa always starts on a Sunday between February 21 and February 27 ( Old style : February 8 to February 14 ). Skammdegi ( `` Short days '' ) Gormánuður ( mid October - mid November, `` slaughter month '' or `` Gór 's month '' ) Ýlir ( mid November - mid December, `` Yule month '' ) Mörsugur ( mid December - mid January, `` fat sucking month '' ) Þorri ( mid January - mid February, `` frozen snow month '' ) Góa ( mid February - mid March, `` Góa 's month, see Nór '' ) Einmánuður ( mid March - mid April, `` lone '' or `` single month '' ) Náttleysi ( `` Nightless days '' ) Harpa ( mid April - mid May, Harpa is a female name, probably a forgotten goddess, first day of Harpa is celebrated as Sumardagurinn fyrsti - first day of summer ) Skerpla ( mid May - mid June, another forgotten goddess ) Sólmánuður ( mid June - mid July, `` sun month '' ) Heyannir ( mid July - mid August, `` hay business month '' ) Tvímánuður ( mid August - mid September, `` two '' or `` second month '' ) Haustmánuður ( mid September - mid October, `` autumn month '' ) Old georgian calendar Main article : Georgian calendar Month Georgian Month Name Transliteration Georgian Other Names Transliteration January აპნისი, აპანი Apnisi, Apani February სურწყუნისი Surtskunisi განცხადებისთვე Gantskhadebistve March მირკანი Mirkani April იგრიკა Igrika May ვარდობისა Vardobisa ვარდობისთვე Vardobistve June მარიალისა Marialisa თიბათვე, ივანობისთვე Tibatve, Ivanobistve July თიბისა Tibisa მკათათვე, კვირიკობისთვე Mkatatve, Kvirikobistve August ქველთობისა Kveltobisa მარიამობისთვე Mariamobistve September ახალწლისა Akhaltslisa ენკენისთვე Enkenistve October სთვლისა Stvlisa ღვინობისთვე Gvinobistve November ტირისკონი Tiriskoni გიორგობისთვე, ჭინკობისთვე Giorgobistve, Chinkobistve December ტირისდენი Tirisdeni ქრისტეშობისთვე Kristeshobistve * NOTE : New Year in ancient Georgia started from September. Old Swedish calendar Torsmånad ( January, ' Torre 's month ' ( ancient god ) ) Göjemånad ( February, ' Goe 's month ' ( ancient goddess ) ) Vårmånad ( March, ' Spring month ' ) Gräsmånad ( April, ' Grass month ' ) Blomstermånad ( May, ' Bloom month ' ) Sommarmånad ( June, ' Summer month ' ) Hömånad ( July, ' Hay month ' ) Skördemånad, Rötmånad ( August, ' Harvest month ' or ' Rotten month ' ) Höstmånad ( September, ' Autumn month ' ) Slaktmånad ( October, ' Slaughter month ' ) Vintermånad ( November, ' Winter month ' ) Julmånad ( December, ' Christmas month ' ) Old English calendar Like the Old Norse calendar, the Anglo - Saxons had their own calendar before they were Christianized which reflected native traditions and deities. These months were attested by Bede in his works On Chronology and The Reckoning of Time written in the 8th century. His months are probably those as written in the Northumbrian dialect of Old English which he was familiar with. The months were so named after the moon ; the new moon marking the end of an old month and start of a new month ; the full moon occurring in the middle of the month, after which the month was named. Æfterra - ġēola mōnaþ ( January, ' After - Yule month ' ) Sol - mōnaþ ( February, ' Sol month ' ) Hrēð - mōnaþ ( March, ' Hreth month ' ) Ēostur - mōnaþ ( April, ' Ēostur month ' ) Ðrimilce - mōnaþ ( May, ' Three - milkings month ' ) Ærra - Liþa ( June, ' Ere - Litha ' ) Æftera - Liþa ( July, ' After - Litha ' ) Weōd - mōnaþ ( August, ' Weed month ' ) Hāliġ - mōnaþ or Hærfest - mōnaþ ( September, ' Holy month ' or ' Harvest month ' ) Winter - fylleþ ( October, ' Winter - filleth ' ) Blōt - mōnaþ ( November, ' Blót month ' ) Ærra - ġēola mōnaþ ( December, ' Ere - Yule ' ) Old hungarian calendar Nagyszombati kalendárium ( in Latin : Calendarium Tyrnaviense ) from 1579. Historically Hungary used a 12 - month calendar that appears to have been zodiacal in nature but eventually came to correspond to the Gregorian months as shown below : Boldogasszony hava ( January, ' month of the happy / blessed lady ' ) Böjtelő hava ( February, ' month of early fasting / Lent ' or ' month before fasting / Lent ' ) Böjtmás hava ( March, ' second month of fasting / Lent ' ) Szent György hava ( April, ' Saint George 's month ' ) Pünkösd hava ( May, ' Pentecost month ' ) Szent Iván hava ( June, ' Saint John ( the Baptist ) 's month ' ) Szent Jakab hava ( July, ' Saint James ' month ' ) Kisasszony hava ( August, ' month of the Virgin ' ) Szent Mihály hava ( September, ' Saint Michael 's month ' ) Mindszent hava ( October, ' all saints ' month ' ) Szent András hava ( November, ' Saint Andrew 's month ' ) Karácsony hava ( December, ' month of Yule / Christmas ' ) Old Egyptian calendar This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. ( January 2015 ) The ancient civil Egyptian calendar had a year that was 365 days long and was divided into 12 months of 30 days each, plus 5 extra days ( epagomenes ) at the end of the year. The months were divided into 3 `` weeks '' of ten days each. Because the ancient Egyptian year was almost a quarter of a day shorter than the solar year and stellar events `` wandered '' through the calendar, it is referred to as Annus Vagus or `` Wandering Year ''. Thout Paopi Hathor Koiak Tooba Emshir Paremhat Paremoude Pashons Paoni Epip Mesori Nisga'a calendar The Nisga'a calendar coincides with the Gregorian calendar with each month referring to the type of harvesting that is done during the month. K'aliiyee = Going North - referring to the Sun returning to its usual place in the sky Buxwlaks = Needles Blowing About - February is usually a very windy month in the Nass River Valley Xsaak = To Eat Oolichans - Oolichans are harvested during this month Mmaal = Canoes - The river has defrosted, hence canoes are used once more Yansa'alt = Leaves are Blooming - Warm weather has arrived and leaves on the trees begin to bloom Miso'o = Sockeye - majority of Sockeye Salmon runs begin this month Maa'y = Berries - berry picking season Wii Hoon = Great Salmon - referring to the abundance of Salmon that are now running Genuugwwikw = Trail of the Marmot - Marmots, Ermines and animals as such are hunted Xlaaxw = To Eat Trout - trout are mostly eaten this time of year Gwilatkw = To Blanket - The earth is `` blanketed '' with snow Luut'aa = Sit In - the Sun `` sits '' in one spot for a period of time French republican calendar Main article : French Republican calendar This calendar was proposed during the French Revolution, and used by the French government for about twelve years from late 1793. There were twelve months of 30 days each, grouped into three ten - day weeks called décades. The five or six extra days needed to approximate the tropical year were placed after the months at the end of each year. A period of four years ending on a leap day was to be called a Franciade. It began at the autumn equinox : Autumn : Vendémiaire Brumaire Frimaire Winter : Nivôse Pluviôse Ventôse Spring : Germinal Floréal Prairial Summer : Messidor Thermidor Fructidor Adhik Maas Purushottam Maas or Adhik Maas is an extra month in the Hindu calendar that is inserted to keep the lunar and solar calendars aligned. `` Purushottam '' is an epithet of Vishnu, to whom the month is dedicated. See also Look up month in Wiktionary, the free dictionary. Maya calendar Chinese calendar Egyptian calendar Ethiopian calendar List of months by year Lunar month Kurdish calendar References Jump up ^ Solomon, Stenson ( 2009 ). Pingelap Non-Sacred Knowledge. Historic Preservation Fund Grant Department of Land and Natural Resources. Jump up ^ Days in each Month - Mnemonics to improve memory Jump up ^ The Boy Mechanic : A Handy Calendar ( 1913 ) from Project Gutenberg ^ Jump up to : Esslemont, J.E. ( 1980 ). Bahá'u'lláh and the New Era ( 5th ed. ). Wilmette, Illinois, USA : Bahá'í Publishing Trust. pp. 178 -- 179. ISBN 0 - 87743 - 160 - 4. Jump up ^ `` What is the Sikh Nanakshahi calendar ''. allaboutsikhs.com. Archived from the original on 2008 - 05 - 10. Retrieved 2008 - 05 - 09. Jump up ^ `` Khmer Chhankitek Calendar '', www.cam-cc.org Jump up ^ Sri Lanka -- Festival Calendar Jump up ^ The Significance of Poya Jump up ^ The Old English Calendar Jump up ^ The Calendar by Marsigli : the ancient Hungarian Calendar Jump up ^ Hónapok nevei Jump up ^ Adhik mass Time Key concepts Past history deep time Present Future Futures studies Far future in religion Far future in science fiction and popular culture Timeline of the far future Eternity Eternity of the world Measurement and standards Chronometry UTC UT TAI Unit of time Planck time Second Minute Hour Day Week Month Year Decade Century Millennium Tropical year Sidereal year Samvatsara Measurement systems Time zone Six - hour clock 12 - hour clock 24 - hour clock Daylight saving time Solar time Sidereal time Metric time Decimal time Hexadecimal time Calendars Gregorian Julian Hebrew Islamic Lunar Solar Hijri Mayan Intercalation Leap second Leap year Clocks Horology History of timekeeping devices Main types astrarium atomic quantum marine sundial sundial markup schema watch water - 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Question: where do you think the length of a month came from
Answer: with the cycle of moon phases; such months (lunations) are synodic months and last approximately 29.53 days