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The new moon phase

In astronomical terminology, the phrase new moon is the lunar phase that occurs when the Moon, in its monthly orbital motion around Earth, lies between Earth and the Sun, and is therefore in conjunction with the Sun as seen from Earth. At this time, the dark (unilluminated) portion of the Moon faces almost directly toward Earth, so that the Moon is not visible to the naked eye.

The original meaning of the phrase new moon was the first visible crescent of the Moon, after conjunction with the Sun. This takes place over the western horizon in a brief period between sunset and moonset, and therefore the precise time and even the date of the appearance of the new moon by this definition will be influenced by the geographical location of the observer. The astronomical new moon, sometimes known as the dark moon to avoid confusion, occurs by definition at the moment of conjunction in ecliptic longitude with the Sun, when the Moon is invisible from the Earth. This moment is unique and does not depend on location, and under certain circumstances it may be coincident with a solar eclipse.

The new moon in its original meaning of first crescent marks the beginning of the month in lunar calendars such as the Muslim calendar, and in lunisolar calendars such as the Hebrew calendar, Hindu calendars, and Buddhist calendar. But in the Chinese calendar the beginning of the month is marked by the dark moon.

Religious use

• The Islamic calendar has retained an observational definition of the new moon, marking the new month when the first Crescent Moon is actually seen, and making it impossible to be certain in advance of when a specific month will begin (in particular, the exact date on which Ramadan will begin is not known in advance). In Saudi Arabia, if the weather is cloudy when the new moon is expected, observers are sent up in airplanes. In Pakistan, there is a "Central Ruet-e-Hilal Committee" comprises of Ulemas (Religious Scholars), which takes help from 150 Observatories of Pakistan Meteorological Department all over the country and announces decision of the sighting of new moon. In Iran a special committee receives observations of every new moon to determine the beginning of each month. This committee uses one hundred groups of observers.

Recently an attempt to unify Muslims on a scientifically calculated worldwide calendar has been adopted by both the Fiqh Council of North America and European Council for Fatwa and Research. The new calculation requires that conjunction occur before sunset in Mecca, Saudi Arabia and that moon set on the following day must take place after sunset. These can be precisely calculated and therefore a unified calendar is imminent if it becomes adopted worldwide. ^[1][2]

• The new moon is quite significant in Hindu calendar. It is believed that new moon can create several fluctuations(negative) in the mental plane. Goddess Kali is worshipped on new moon night to relax these fluctuations.

• The new moon is the beginning of the month in the Chinese calendar. Some Buddhist Chinese keep a vegetarian diet on the new moon and full moon each month.

• The new moon signifies the start of every Jewish month, and is considered an important date and minor holiday in the Hebrew calendar. The modern form of the calendar is a rule-based lunisolar calendar, akin to the Chinese calendar, measuring months defined in lunar cycles as well as years measured in solar cycles, and distinct from the purely lunar Islamic calendar and the almost entirely solar Gregorian calendar.

• The native messianic Pentecostal group, the New Israelites of Peru, keeps the new moon as a Sabbath of rest. As an evangelical church, it follows the Bible's teachings that God sanctified the seventh-day Sabbath, now largely known as Saturday, and the new moons in addition to it. See Ezekiel 46:1, 3. No work may be done from dusk until dusk, and the services run for 11 hours, although a large number spend 24 hours within the gates of the temples, sleeping and singing praises throughout the night.

• The new moon is also an important event in Wicca.

• The new moon is also important in astrology, as is the full moon.

Determining new moons: an approximate formula

The time interval between new moons—a lunation—is variable. The mean time between new moons, the synodic month, is about 29.53... days. An approximate formula to compute the mean moments of new moon (conjunction between Sun and Moon) for successive months is:

where N is an integer, starting with 0 for the first new moon in the year 2000, and that is incremented by 1 for each successive synodic month; and the result d is the number of days (and fractions) since 2000-01-01 00:00:00 reckoned in the time scale known as Terrestrial Time (TT) used in ephemerides.

To obtain this moment expressed in Universal Time (UT, world clock time), add the result of following approximate correction to the result d obtained above:

days

Periodic perturbations change the time of true conjunction from these mean values. For all new moons between 1601 and 2401, the maximum difference is 0.592 days = 14h13m in either direction. The duration of a lunation (i.e. the time from new moon to the next new moon) varies in this period between 29.272 and 29.833 days, i.e. −0.259d = 6h12m shorter, or +0.302d = 7h15m longer than average ^[3].^[4] This range is smaller than the difference between mean and true conjunction, because during one lunation the periodic terms cannot all change to their maximum opposite value.

See the article on the full moon cycle for a fairly simple method to compute the moment of new moon more accurately.

The long-term error of the formula is approximately: 1 cy² seconds in TT, and 11 cy² seconds in UT (cy is centuries since 2000; see section Explanation of the formulae for details.)

Explanation of the formula

The moment of mean conjunction can easily be computed from an expression for the mean ecliptic longitude of the Moon minus the mean ecliptic longitude of the Sun (Delauney parameter D). Jean Meeus gave formulae to compute this in his popular Astronomical Formulae for Calculators based on the ephemerides of Brown and Newcomb (ca. 1900); and in his 1st edition of Astronomical Algorithms ^[5] based on the ELP2000-85 ^[6] (the 2^nd edition uses ELP2000-82 with improved expressions from Chapront et al. in 1998). These are now outdated: Chapront et al. (2002) ^[7] published improved parameters. Also Meeus's formula uses a fractional variable to allow computation of the four main phases, and uses a second variable for the secular terms. For the convenience of the reader, the formula given above is based on Chapront's latest parameters and expressed with a single integer variable, and the following additional terms have been added:

constant term:

• Like Meeus, apply the constant terms of the aberration of light for the Sun and light-time correction for the Moon ^[8] to obtain the apparent difference in ecliptic longitudes:

Sun: +20.496" ^[9]

Moon: −0.704" ^[10]

Correction in conjunction: −0.000451 days.^[11]

• For UT: at 1 January 2000, ΔT (= TT − UT ) was +63.83 s ^[12]; hence the correction for the clock time UT = TT − ΔT of the conjunction is:

−0.000739 days.

quadratic term:

• In ELP2000–85 (see Chapront et alii 1988), D has a quadratic term of −5.8681"T²; expressed in lunations N, this yields a correction of +87.403 × 10^–12N² ^[13] days to the time of conjunction. The term includes a tidal contribution of 0.5×(−23.8946 "/cy²). The most current estimate from Lunar Laser Ranging for the acceleration is (see Chapront et alii 2002): (−25.858 ±0.003)"/cy². Therefore the new quadratic term of D is = -6.8498"T² ^[14]. Indeed the polynomial provided by Chapront et alii (2002) provides the same value (their Table 4). This translates to a correction of +14.622 × 10⁻¹²N² days to the time of conjunction; the quadratic term now is:

+102.026 × 10⁻¹²N² days.

• For UT: analysis of historical observations show that ΔT has a long-term increase of +31 s/cy² ^[15]. Converted to days and lunations ^[16], the correction from ET to UT becomes:

−235 × 10⁻¹²N² days.

The theoretical tidal contribution to ΔT is about +42 s/cy² ^[17]; the smaller observed value is thought to be mostly due to changes in the shape of the Earth ^[18]. Because the discrepancy is not fully explained, uncertainty of our prediction of UT (rotation angle of the Earth) may be as large as the difference between these values: 11 s/cy². The error in the position of the Moon itself is only maybe 0.5"/cy² ^[19], or (because the apparent mean angular velocity of the Moon is about 0.5"/s), 1 s/cy² in the time of conjunction with the Sun.

See also

• Black moon
• Blue moon
• Ecclesiastical new moon
• Full moon
• Half moon
• Metonic cycle
• Lunar Cycle

References

External links

• Moon Watch site of the Nautical Almanac Office
• Sacred Astronomy from Zaytuna institute
• CrescentWatch.org from Zaytuna Institute
• Moon sighting Committee World-wide of Khalid Shaukat
• Moon Sighting from Committee For Crescent Observation, Intl.
• Islamic Crescent Observation Project
• The Length of the Lunar Cycle (numerical integration analysis)
• Predicting the First Visibility of the Lunar Crescent
• hilalsighting.org website

From BibleWiki

The biblical New Moon (opposite of the full moon) refers to how we see this event from earth with the naked eye. The astronomical new moon refers to how we see this event though a telescope with zero illumination which usually precedes the biblical New Moon by about a day or so. The biblical New Moon refers to the first day of the confirmed sighting of the newly waxing crescent moon in the early evening sky. The newly waxing crescent moon is only a faint sliver barely perceivable to the naked eye and only for a short time the first evening it is sighted. This confirmed New Moon sighting marks the beginning of the month in Biblical and Islamic societies today as well as other societies in the past.

In order to unite all Jews in the Diaspora in regard to keeping the Holydays, the Jews adopted a rule-based fixed-arithmetic lunisolar calendar system to substitute the New Moon Sighting. The principles and rules of the current calendar were fully described by Maimonides in 1178 CE in the Mishneh Torah. The Jewish calendar used today is often one or two days behind or ahead of the actual New moon sighting, whether one reckons the sighting from Jerusalem or from where ever one lives.

The period of New Moon was, in pre-exilic times, celebrated by cessation of labor;(see 1Sam 20:18-34; 2Kg 4:23; Amos viii. 5; Hos 2:13 [A. V. 11]; Ezek 46:3); but it lost its importance during the Exile (see Sabbath) and was observed mainly as the determining factor of the calendar with its festivals. In the latter period only the women—who in pagan times were especially attached to the "queen of heaven" (Jer 44:15-19)—refrained from work on New Moon, the reason given being that they were privileged to celebrate it because they had not been as willing to worship the golden calf as the men (Yer. Pes. iv. 30d; Pirḳe R. El. xlv.; Ṭur, Oraḥ Ḥayyim, 917); the men were allowed to work (Ḥag. 18a; 'Ar. 10b). In the Temple, New Moon was celebrated by special sacrifices (Num 28:11-15; 2Chr 2:4, viii. 13; Ezra iii. 5; Neh 10:33) and by the blowing of the trumpet (Num 10:10). Of the greatest significance, however, was the proclamation of New Moon ("Ḳiddush ha-Ḥodesh") by the president of the Sanhedrin (R. H. ii. 7)—originally, of course, by the high priest—just as in Rome the Pontifex Maximus fixed New Moon by proclamation (whence the name Calendar). The Sanhedrin was assembled in the courtyard ("bet ya'azek") of Jerusalem on the 30th of each month from morning to evening, waiting for the reports of those appointed to observe the new moon; and after the examination of these reports the president of the Sanhedrin, in the presence of at least three members, called out: "The New Moon is consecrated"; whereupon the whole assembly of people twice repeated the words: "It is consecrated" (R. H. ii. 5-7; Sanh. 102). The blowing of the shofar at the time of the proclamation of New Moon was practised also in the Babylonian schools (Sanh. 41b). The proclamation of New Moon was retained in the liturgy, but was transferred to the Sabbath preceding. The following is the formula:

The Reader (probably at first the most prominent man of the community): "He who wrought miracles for our fathers and redeemed them from slavery unto freedom, may He speedily redeem us and gather our dispersed ones from the four corners of the earth. So let us say, Amen!

"[Hear ye] All Israel ["ḥaberim"="members of the ḥaburah"]: The New Moon shall be on the . . . day of the coming week! May it come to us and all Israel for good!"

The Congregation: "May the Holy One, blessed be He! renew unto us and unto all His people the House of Israel for life and peace, for gladness and joy, for [Messianic] salvation and consolation! So let us say, Amen!"

In Sephardic congregations the prayer "Yehi Raẓon" is recited, of which one paragraph reads:

"May it be the will of our Father in heaven that good tidingsof [Messianic] salvation and consolation be heard and received by us, that He may gather our dispersed ones from the four corners of the earth. So let us say, Amen!"

The relation of New Moon to the redemption of Israel was expressed also in the benediction recited by the members of the "ḥaburah" at the New Moon banquet, and preserved in a late corrupt version in Masseket Soferim, xix. 9, from which the benediction at the sight of the new moon (see New Moon, Blessing of the) was probably derived at a later time (see Müller, "Masechet Soferim," 1878, p. 272). It reads as follows:

"Be blessed, O Lord, O God, King of the Universe, who hast brought up the teachers in the circle of the school and taught them the knowledge of the seasons. As Thou hast appointed the time for the circuit of the moon, so hast Thou also selected the wise who are skilled in the counting and fixing of the seasons, as it is said: 'He appointed the moon for seasons' [[[Book of Psalms|Ps]] 104¹⁹]. For 'as the new heaven and the new earth which I will make shall remain before Me, saith the Lord, so shall your seed and your name remain.' Blessed be Thou, O Lord, who reneweth Israel and the moon."

This is followed by Ps. cvi. and cvii., and II Chron. xx.-xxi.; at the close occurs a special prayer for the coming of Elijah and of the Messiah. Then comes the proclamation: "The New Moon be consecrated!" which is repeated in many strains by the ḥaberim.

Occasionally the messengers who announced the proclamation of New Moon to the Jews of the various lands were given mysterious watchwords alluding to the Messianic hope. Such was the one given by Judah ha-Nasi (R. H. 25a; see Apostle; New Moon, Blessing of the). The waxing and waning of the moon reminded the sages of Israel's renewal (Pirḳe R. El. li.), especially with reference to the prophecy that in the future the "light of the moon will be like the light of the sun" (Isa 30:26), as well as of the Messiah, who for certain times is concealed and then again revealed (see Messiah). This view casts light also on the benediction prescribed at the sight of the new moon.

Bibliography: Beer, 'Abodat Yisrael, 1868, pp. 232, 337-339; Brück, Rabbinische Ceremonial-Gebräuche, 1837, pp. 33-40.