The month is a unit of time, used with calendars, which is approximately as long as some natural period related to the motion of the Moon; month and Moon are cognates. For other uses see Time (disambiguation Time is a component of a measuring system used to sequence events to compare the durations of The word Calendar consist of two words 1 Cal ( in Pashto means Year in Hindi and Persian is Sal- also means Year The orbital period is the time taken for a given object to make one complete Orbit about another object Cognates in Linguistics are words that have a common origin They may occur within a language such as shirt and skirt as two English words descended from The traditional concept arose with the cycle of moon phases; such months (lunations) are synodic months and last approximately 29. Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth 53 days. A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the From excavated tally sticks, researchers have deduced that people counted days in relation to the Moon's phases as early as the Paleolithic age. A tally (or tally stick) was an ancient memory aid device to record and document numbers quantities or even messages The term Paleolithic (or Palaeolithic) (from Greek παλαιός palaios, " Old " and λίθος Lithos, "stone" Synodic months are still the basis of many calendars today.
The motion of the Moon in its orbit is very complicated and its period is not constant. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star Moreover, many cultures (most notably those using the ancient Hebrew (Jewish) calendar and the Islamic calendar) start a month with the first appearance of the thin crescent of the new moon after sunset over the western horizon. The Hebrew calendar (הלוח העברי ha'luach ha'ivri) or Jewish calendar is a Lunisolar calendar used by Jews for predominantly religious The Islamic calendar or Muslim calendar ( Arabic: التقويم الهجري at-taqwīm al-hijrī; Persian: تقویم هجری قمری This article is about the lunar phase for other uses see New Moon (disambiguation. 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 in these calendars can not be accurately predicted. Most Jews currently follow a precalculated calendar, but the Karaites rely on actual moon observations. Karaite Judaism or Karaism (ˈkærəˌaɪt ˈkærəˌɪzəm) is a Jewish movement NOTE The word sect should not be used without defining it first and
The period of the Moon's orbit as defined with respect to the celestial sphere is known as a sidereal month because it is the time it takes the Moon to return to a given position among the stars (Latin: sidus): 27. In Astronomy and Navigation, the celestial sphere is an imaginary rotating Sphere of "gigantic Radius " A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. 321661 days (27 d 7 h 43 min 11. 5 s). This type of month has been observed among cultures in the Middle East, India, and China in the following way: they divided the sky into 27 or 28 lunar mansions, defined by asterisms (apparent groups of stars), one for each day of the sidereal month. A nakshatra ( Devanagari: नक्षत्र or lunar mansion is one of the 27 or 28 divisions of the sky identified by the prominent star(s in them that the In Astronomy, an asterism is a pattern of Stars seen in Earth's sky which is not an official Constellation.
It is customary to specify positions of celestial bodies with respect to the vernal equinox. An equinox is the event of the Sun passing over the Earth's equator in its annual cycle Because of precession, this point moves back slowly along the ecliptic. Precession refers to a change in the direction of the axis of a rotating object The ecliptic is the apparent path that the Sun traces out in the sky during the year Therefore it takes the Moon less time to return to an ecliptic longitude of zero than to the same point amidst the fixed stars: 27. 321582 days (27 d 7 h 43 min 4. 7 s). This slightly shorter period is known as tropical month; cf. the analogous tropical year of the Sun. A tropical year (also known as a solar year) is the length of time that the Sun takes to return to the same position in the cycle of seasons as seen from Earth The Sun (Sol is the Star at the center of the Solar System.
Like all orbits, the Moon's orbit is an ellipse rather than a circle. The orbit of the Moon around the Earth is completed in approximately 27 However, the orientation (as well as the shape) of this orbit is not fixed. In particular, the position of the extreme points (the line of the apsides: perigee and apogee), makes a full circle (lunar precession) in about nine years. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from There are two important Precessional motions in the Orbit of the Moon. It takes the Moon longer to return to the same apsis because it moved ahead during one revolution. This longer period is called the anomalistic month, and has an average length of 27. 554551 days (27 d 13 h 18 min 33. 2 s). The apparent diameter of the Moon varies with this period, and therefore this type has some relevance for the prediction of eclipses (see Saros), whose extent, duration, and appearance (whether total or annular) depend on the exact apparent diameter of the Moon. An eclipse is an astronomical event that occurs when one Celestial object moves into the shadow of another Saros or Sáros may refer to Saros cycle, a method for predicting solar eclipses SS Saros, a shipwreck off the southeast coast The apparent diameter of the full moon varies with the full moon cycle which is the beat period of the synodic and anomalistic month, and also the period after which the apsides point to the Sun again. Full moon is a Lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. The full moon cycle is a cycle of about 14 Lunations over which Full moons vary in apparent size and age (time since New moon)
Also called the nodical month. The orbit of the moon lies in a plane that is tilted with respect to the plane of the ecliptic: it has an inclination of about five degrees. Inclination in general is the Angle between a Reference plane and another plane or axis of direction The line of intersection of these planes defines two points on the celestial sphere: the ascending node, when the moon's path crosses the ecliptic as the moon moves into the northern hemisphere, and descending node when the moon's path crosses the ecliptic as the moon moves into the southern hemisphere. An orbital node is one of the two points where an Orbit crosses a Plane of reference which it is inclined to An orbital node is one of the two points where an Orbit crosses a Plane of reference which it is inclined to The draconic or nodical month is the average interval between two successive transits of the moon through its ascending node. Because of the sun's gravitational pull on the moon, the moon's orbit gradually rotates westward on its axis, which means the nodes gradually rotate around the earth. As a result, the time it takes the moon to return to the same node is shorter than a sidereal month. It lasts 27. 212220 days (27 d 5 h 5 min 35. 8 s). The plane of the moon's orbit precesses over a full circle in about 18. Precession refers to a change in the direction of the axis of a rotating object 6 years.
Because the moon's orbit is inclined with respect to the ecliptic, the sun, moon, and earth are in line only when the moon is at one of the nodes. Whenever this happens a solar or lunar eclipse is possible. An eclipse is an astronomical event that occurs when one Celestial object moves into the shadow of another The name "draconic" refers to a mythical dragon, said to live in the nodes and eat the sun or moon during an eclipse.
This is the average period of the Moon's revolution with respect to the sun. The synodic month is responsible for the moon's phases, because the Moon's appearance depends on the position of the Moon with respect to the Sun as seen from the Earth. Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth While the moon is orbiting the earth, the Earth is progressing in its orbit around the Sun. This means that after completing a sidereal month the Moon must move a little farther to reach the new position of the Earth with respect to the Sun. This longer period is called the synodic month from the Greek syn hodô (σὺν ὁδῴ), meaning "with the way [of the sun]". Because of perturbations in the orbits of the Earth and Moon, the actual time between lunations may range from about 29. Lunation is the mean time for one Lunar phase cycle (ie the Synodic period of the Moon) 27 to about 29. 83 days. The long-term average duration is 29. 530589 days (29 d 12 h 44 min 2. 9 s). The synodic month is used in the Metonic cycle. Metonic cycle or Enneadecaeteris in Astronomy and Calendar studies is a particular approximate common multiple of the Tropical year
Here is a list of the average length of the various astronomical lunar months . These are not constant, so a first-order (linear) approximation of the secular change is provided:
|sidereal month||27. Terrestrial Time (TT is the modern astronomical standard for the passage of time on the surface of the Earth (for civil purposes Coordinated Universal 321661547 + 0. 000000001857 × y days|
|tropical month||27. 321582241 + 0. 000000001506 × y days|
|anomalistic month||27. 554549878 − 0. 000000010390 × y days|
|draconic month||27. 212220817 + 0. 000000003833 × y days|
|synodic month||29. 530588853 + 0. 000000002162 × y days|
Note: time expressed in Ephemeris Time (more precisely Terrestrial Time) with days of 86,400 SI seconds. Ephemeris Time ( ET) is a time scale used in Ephemerides of celestial bodies in particular the Sun (as observed from the Earth Moon planets and other members of Terrestrial Time (TT is the modern astronomical standard for the passage of time on the surface of the Earth (for civil purposes Coordinated Universal The second ( SI symbol s) sometimes abbreviated sec, is the name of a unit of Time, and is the International System of Units y is years since the epoch (2000), expressed in Julian years of 365. 25 days. Note that for calendrical calculations, one would probably use days measured in the time scale of Universal Time, which follows the somewhat unpredictable rotation of the Earth, and progressively accumulates a difference with ephemeris time called ΔT. This article is about the time difference for the temperature difference see Psychrometrics.
At the simplest level, all lunar calendars are based on the approximation that 2 lunations last 59 days: a 30 day full month followed by a 29 day hollow month — but this is only marginally accurate and quickly needs correction by using larger cycles, or the equivalent of leap days. Leap years Although the modern calendar counts a year as 365 days a complete revolution around the sun takes approximately 365 days and 6 hours
Second, the synodic month does not fit easily into the year, which makes constructing accurate, rule-based lunisolar calendars difficult. A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun 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). Metonic cycle or Enneadecaeteris in Astronomy and Calendar studies is a particular approximate common multiple of the Tropical year A tropical year (also known as a solar year) is the length of time that the Sun takes to return to the same position in the cycle of seasons as seen from Earth However, a Metonic calendar (such as the Hebrew calendar) will drift against the seasons by about 1 day every 200 years. The Hebrew calendar (הלוח העברי ha'luach ha'ivri) or Jewish calendar is a Lunisolar calendar used by Jews for predominantly religious
The problems of creating reliable lunar calendars may explain why solar calendars, having months which no longer relate to the phase of the moon, and being based only on the motion of the sun against the sky, have generally replaced lunar calendars for civil use in most societies. A solar calendar is a Calendar whose dates indicate the position of the earth on its revolution around the Sun (or equivalently the apparent position of the sun moving
The average month in the Gregorian calendar has a length of 30. 4167 days or 4. 345 weeks in a non-leap year and 30. 5 days or 4. 357 weeks in a leap year, or 30. 436875 days in a mean Gregorian month overall (364. 2425 ÷ 12).
Months existing in the Roman calendar in the past include:
The famous mnemonic Thirty days hath September is the most common way of teaching the lengths of the months in the English-speaking world. A mnemonic device (nəˈmɒnɪk is a Memory aid Commonly met mnemonics are often verbal something such as a very short poem or a special word used to help a person remember Thirty days hath September is a traditional English Mnemonic rhyme of which many variants are commonly used in English-speaking countries to remember the lengths
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. 
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 before the ides, i. The Roman calendar changed its form several times in the time between the foundation of Rome and the fall of the Roman Empire. e. , on the fifth or the seventh. The calends are always the first day of the month. The Calends ( Latin Kalendae "the called" gen plural - arum) correspond to the first days of each month of the Roman calendar.
This calendar was proposed during the French Revolution, and used by the French government for about twelve years from late 1793. The French Republican Calendar or French Revolutionary Calendar was a Calendar proposed during the French Revolution, and used by the French government 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:
There are also twelve months in the Islamic calendar. Vendémiaire was the first Month in the French Republican Calendar. Brumaire was the second Month in the French Republican Calendar. Frimaire was the third Month in the French Republican Calendar. Nivôse (also Nivose) was the fourth Month in the French Republican Calendar. Pluviôse (also Pluviose) was the fifth Month in the French Republican Calendar. Ventôse (also Ventose) was the sixth Month in the French Republican Calendar. Germinal was the seventh Month in the French Republican Calendar. For the ship class see Floréal class frigate Floréal was the eighth Month in the French Republican Calendar. Prairial was the ninth Month in the French Republican Calendar. Messidor was the tenth Month in the French Republican Calendar. Thermidor was the eleventh Month in the French Republican Calendar. Fructidor was the twelfth Month in the French Republican Calendar. The Islamic calendar or Muslim calendar ( Arabic: التقويم الهجري at-taqwīm al-hijrī; Persian: تقویم هجری قمری They are named as follows:
The Hebrew calendar has 12 or 13 months. Muharram ( Arabic: ar محرم is the first month of the Islamic calendar. Safar (ar صفر is the second month in the Islamic calendar. Rabi' al-awwal (ar ربيع الأول is the third month in the Islamic calendar. Rabi’ al-Thani (ar ربيع الثاني the second of spring) is the fourth month in the Islamic Calendar. Jumada al-awwal (ar جمادى الأول is the fifth month in the Islamic calendar. Jumada al-thani (ar جمادى الآخر أو جمادى الثاني is the sixth month in the Islamic Calendar. Rajab ( Arabic: ar رجب is the seventh month of the Islamic calendar. Sha'aban ( Arabic: ar شعبان is the eighth month of the Islamic calendar. Ramadan or Ramadhan or Ramazan ( Arabic: ar رمضان is the ninth month of the Islamic calendar. Shawwal (ar شوّال is the tenth month of the lunar Islamic calendar. Dhu al-Qi'dah (ar ذو القعدة is the eleventh month in the Islamic calendar. Dhu al-Hijja (ar ذو الحجة is the twelfth and final month in the Islamic Calendar. The Hebrew calendar (הלוח העברי ha'luach ha'ivri) or Jewish calendar is a Lunisolar calendar used by Jews for predominantly religious
Adar 1 is only added 7 times in 19 years. This article is about the Jewish month of Nisan See Nissan Motors for the automobile manufacturer Iyar ( Hebrew: אִייָר or אִיָּר, Standard Iyyar Tiberian ʾIyyār; Sivan ( Hebrew: סִיוָן, Standard Sivan Tiberian Sîwān; from Akkadian Av ( Hebrew: אָב, Standard Av Tiberian ʾĀḇ; from Akkadian abu Elul (אֱלוּל Standard Elul Tiberian ʾĔlûl; from Akkadian elūlu) is the twelfth Tishrei (or Tishri) (ˈtɪʃri or) ( Hebrew: תִּשְׁרֵי ( תִּשְׁרִי) Standard Tišre Cheshvan ( Hebrew: חֶשְׁוָן, Standard Ḥešvan Tiberian Ḥešwān) short for For the Warhammer Fantasy location see Kislev (Warhammer Kislev ( Hebrew: כִּסְלֵו, Standard Tevet ( Hebrew: טֵבֵת, Standard Tevet; Ashkenazi Teves; Tiberian Shevat (or Shvat) ( Hebrew: שְׁבָט, Standard Šəvat Tiberian Šəḇāṭ Adar ( Hebrew: אֲדָר, Standard Adar Tiberian ʾĂḏār; from Akkadian Intercalation is the insertion of a leap day week or month into some calendar years to make the calendar follow the seasons or moon phases Adar ( Hebrew: אֲדָר, Standard Adar Tiberian ʾĂḏār; from Akkadian In ordinary years, Adar 2 is simply called Adar.
The Hindu Calendar has various systems of naming the months. The Hindu calendar used in ancient times has undergone many changes in the process of regionalization and today there are several regional Indian Calendars, as The months in the lunar calendar are:
These are also the names used in the Indian national calendar for the newly redefined months. Chaitra ( Hindi: चैत cait or चैत्र caitr) is a Month of the Hindu calendar. Vaisakha' (Indian month -(march बैसाख baisectyz (or uशाखgv viashykh) is a Month of the Sri Lankan (Indian calendar Jyeshta ( Hindi: जेठ jeṭ or ज्येष्ठ jyeṣṭ) is a Month of the Hindu calendar, also known Aashaadha ( Hindi: आसाढ़ aasaarh or आषाढ aaṣaaḍh) is a Month of the Hindu calendar. Shraavana ( Hindi: सावन saavan or श्रावण shraavan) is a Month of the Hindu calendar, also Bhaadra or Bhadrapada ( Hindi: भादों bhaado or भाद्रपद bhaadrapad) is a Month of the Hindu See Ashvins for the divine twins Ashvin ( Hindi: क्वार kvaar, Bangla: আশ্বিন Kartikay also know as Subhramanya Kartik or Kartikkeya is a central deity of the Hindu tradtion of India. Agrahayana ( Hindi: अगहन agahan) is a Month of the Hindu calendar. Pausha ( Hindi: पूस puus or पौष pauṣ) is a Month of the Hindu calendar, also know as Poush Maagha (माघ might be confused with the Nakshatra Magha (मघा Maagha ( Hindi: माघ maagh) is a Phalguna ( Hindi: फागुन phaagun or फाल्गुन phaalgun, Tamil: பங்குனி The Indian national calendar (sometimes called Saka calendar) is the official civil calendar in use in India.
The names in the solar calendar are just the names of the zodiac sign in which the sun travels. Zodiac denotes an annual cycle of twelve stations along the Ecliptic, the apparent path of the sun across the heavens through the Constellations that divide the ecliptic They are
The Iranian / Persian calendar, currently used in Iran and Afghanistan, also has 12 months. Aries ( ram, symbol, Unicode ♈ is one of the Constellations of the Zodiac. Taurus (it looks like a bull (ˈtɔrəs bull, symbol, Unicode ♉ is one of the Constellations of the Zodiac. Gemini (ˈgɛmɪnaɪ Twins, symbol, Unicode ♊ is one of the Constellations of the Zodiac known as "the twins" Cancer ( Crab, symbol, Unicode ♋ is one of the twelve Constellations of the Zodiac. Leo (ˈliːoʊ Lion, symbol, Unicode ♌ is a Constellation of the Zodiac. Virgo ( Virgin, symbol, Unicode ♍ is a Constellation of the Zodiac. Libra (ˈliːbrə balance, symbol, Unicode ♎ is a Constellation of the Zodiac. Scorpius ( Latin for Scorpion, symbol, Unicode ♏ is one of the Constellations of the Zodiac. Capricornus ( Latin for "horned (male Goat " or "goat horn " is one of the Constellations of the Zodiac. Aquarius ( Water -bearer or cup-bearer is the eleventh sign of the Zodiac, situated between Capricornus and Pisces. Pisces (ˈpaɪsiːz Fish (plural symbol, Unicode ♓ is a Zodiac Constellation which lies between Aquarius to the west and Aries }The Tamil Calendar is used in Tamil Nadu, Kerala and Puducherry in India, and by the Tamil population in Malaysia, The Iranian calendar or Solar Hejri (تقویم هجری شمسی؛ سالنمای هجری خورشیدی Taqwim Hejri Shamsi Salanmay Hejri Khurshidi) is an astronomical For a topic outline on this subject see List of basic Iran topics. Afghanistan /æfˈgænɪstæn/ officially the Islamic Republic of Afghanistan ( Pashto: د افغانستان اسلامي جمهوریت, The Persian names are included in the parentheses.
The old Icelandic calendar is not in official use anymore, but some Icelandic holidays and annual feasts are still calculated from it. In Zoroastrian doctrine a fravashi ( Avestan fravaši; Middle Persian fraward, frawahr, frohar, frawash Asha ( aša) or arta is the Avestan language term for a concept of cardinal importance to Zoroastrian theology and doctrine Tishtrya (Tištrya is the Avestan language name of an Zoroastrian benevolent divinity associated with life-bringing rainfall and fertility ae Ameretat ( ae Amərətāt) is the Avestan language name of the Zoroastrian divinity/divine concept of "not dying Shahrivar is the sixth month in the Iranian/Persian calendar. Apas ( ae-Latn āpas) is the Avestan language term for "the waters" which&mdashin its innumerable Atar ( ātar, Avestan) is the Zoroastrian concept for "burning and unburning fire" and "visible and invisible fire" (Mirza 1987389 Dey (Arabic داي from Turkish Dayı) was the title given to the rulers of the Regency of Algiers ( Algeria) and Tunis ( Tunisia) under The Iranian calendar or Solar Hejri (تقویم هجری شمسی؛ سالنمای هجری خورشیدی Taqwim Hejri Shamsi Salanmay Hejri Khurshidi) is an astronomical 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. A week (also called sennight or sevennight) is a unit of Time longer than a Day and shorter than a Month. A date in a calendar is a reference to a particular day represented within a Calendar system Hence Þorri always starts on a Friday sometime between January 19 and January 25 (Old style: January 9 to January 15) , Góa always starts on a Sunday between February 18 and February 24 (Old style: February 8 to February 14). Events 1419 - Hundred Years' War: Rouen surrenders to Henry V of England completing his reconquest of Normandy. Events 41 - After a night of negotiation Claudius is accepted as Roman Emperor by the Senate The Julian calendar, a reform of the Roman calendar, was introduced by Julius Caesar in 46 BC and came into force in 45 BC (709 Ab urbe condita Events 475 - Byzantine Emperor Zeno is forced to flee his capital at Constantinople. Events 588 BC - Nebuchadrezzar II of Babylon lays siege to Jerusalem under Zedekiah 's reign Events 3102 BC - Epoch (origin of the Kali Yuga. 1229 - The Sixth Crusade: Frederick II Holy Events 303 - Galerius, Roman Emperor, publishes his edict that begins the persecution of Christians in his portion of the The Julian calendar, a reform of the Roman calendar, was introduced by Julius Caesar in 46 BC and came into force in 45 BC (709 Ab urbe condita Events 421 - Constantius III becomes co- Emperor of the Western Roman Empire. Events 842 - Charles the Bald and Louis the German swear the Oaths of Strasbourg in the French and German
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".
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