Then Hazrat Imam Kazim (aleyhi s-salam) said: «We know this science and we don't deny it but we don't talk about it». Harun said to Hazrat Imam Kazem: « O Mõssa I implore you by God, don't reveal this knowledge to the ignorants and the common people, so that no one can speak against you, preserve this science of the common people and return to the shrine of your ancestor (peace be upon him and his descendants). » Then Harun said: « I have one more question, I conjure you to answer me». Hazrat Imam Kazem (aleyhi s-salam) said: «Ask» Harun said: « I implore you by the right of the tomb and the minbar of Rasul Allah (salla llah aleyhi wa aaleh) and the right of your relationship and your closeness to him (salla llah aleyhi wa aaleh), inform me about do you will die before me or will I die before you? ». Because you are aware of this subject by astronomy, Hazrat Imam Mõssa Kazem (aleyhi s-salam) said: «Give me your protection and I will answer». Harun said: «You have my protection», Hazrat (aleyhi s-salam) said: «I will die before you. I never lie and my death is near» .

Holy Qoran, sura Al-An'am, Verses 75, sura As-Saffat, Verses 88 and 89, sura Al-Waqi'a, Verses 76, sura An-Nazi'at, Verses 5, sura An-Nahl, Verses 16,
Faraj al-mahmum bemaerefate elm-e-nojum, Sayyed ibn Tawoos, p.108 - Bihar al-Anwar Vol.58, p.254

* Accursed Mamoon asked to Hazrat Imam Reza (aleyhi s-salam) about astronomy (astrology)? Hazrat (aleyhi s-salam) said: «This science is right at it's base, the first person who has spoken about astronomy is the prophet Idriss (aleyhi s-salam). Dhulqarnain in astronomy was an expert. The basis of this science has been bequeathed to the prophets by God it is a part of all the knowledge that has been specifically revealed to them and the astronomers don't have access to the profundity and subtlety of this science, thus true and false are mixed together».
Faraj al-mahmum, Sayyed ibn Tawoos, p.108 - Bihar al-Anwar Vol.58, p.254.

The astronomy and astrology institute of Hayaat-aĕlaa Fondation with the guidance and under the supervision and direction of Daar al-Maĕaaref al-Ilaahiyyah is dedicated to the compilation of these divine knowledges, for their compilation, we refer to the Revelation's Speech and the Discourse of the Custodians of the Revelation (aleyhimo s-salam) the investigations of the greatest scholars in the history of astronomy and also the latest scientific achievements of modern valid international centers today are also used.

In islamic astronomy,the word month is a term which refers to the period determined by the Moon’s trajectory.

A lunar month ؛ is the period during which the Moon’s phases succeed each other.During this period the Moon performs a complete rotation around the Earth. This Moon cycle is also called lunation.

The average value of the synodic month is about 29.5 days. As part of precise lunar observation, the average value of the synodic month has been determined accurately to 29.53059 days: 29 days, 12 hours, 44 minutes and 2/78 seconds. This average duration is employed in the elaboration of numerous lunar calendars. Note: the duration of the synodic month with regard to its average duration may vary up to 13 hours.

The lunar calendar: The oldest and the most common calendar is the lunar calendar. In this calendar the duration of the lunar month is almost the duration of a lunation, so the first day of each month is nearly coinciding with new Moon.

Interlunar phases or Moon in “taȟte šoãĕ”:
In every lunar month, the last two days in the months of 29 days and the last three days in the months of 30 days, the Moon is invisible. In ancient Islamic astronomy this Moon’s phase has a special name: we say that the Moon is in “taȟte šoãĕ” (تحت الشعاع) which means «under the radiance (of the Sun) ». Indeed, in this period due to the closeness of the Moon to the Sun, the Moon is under the radiance of the Sun and it is the shadowed Moon’s side which making face to the Earth: the powerful radiation of the Sun prevents the visibility of the Moon. In the months of 30 days, this Moon’s phase starts with the sunrise on the morning of 27th and persists until sunset on 30th. In the months of 29 days this Moon’s phase starts with the sunset on 27th and continues until sunset on 29th. In the middle of these phase, the Moon is in Conjunction with the Sun.

Moon Phases Calendar : This calendar is determined with naked eye observations of the Moon’s phases. In this type of calendar everybody among scientists and people with observing the sky can find what night of the month it is. The general need of this type of calendar aroused its publication, so we have composed it and made its publication.

×       For determining the first day of the lunar month, is two methods used in astronomical calendars: : Islamic Calendars based on the Calculated First Visibility of the Lunar Crescent and Arithmetical or Tabular Islamic Calendar (Lunar Calendar).

Islamic Calendars based on the Calculated first visibility of the Hilal: This method is based on an astronomical calculation which predicts the observation possibilities of the Hilal and the time of its visibility. This method in lunar calendars is commonly used. However, according to the Shariah, the criterion which determines the first day of the lunar month is the collective observation of the Hilal. The opinion of the majority of Muslim jurists of all branches of Islam is that the astronomical calculation is not equivalent to the observation of the Hilal with naked eye. Therefore this calculation can’t be used as a legal argument. This method used in most calendars does not paid attention to this point and can’t be accepted, especially that often the forecast of the Hilal visibility and its observation with the naked-eye doesn’t coincide.

First point : Despite the technological possibilities of modernity to observe the Hilal and precise calculations for determining it, the Muslims and also non-Muslim scientists at various levels among the scholars and the public, continue to strive for determining Moon’s age and the Hilal visibility. International and scientific institutes of astronomy continually publish calculations and details about it. But the specificities of Moon’s motions, its position relative to the Sun and weather variables of the Earth make difficulties to determinate the first day of the lunar month according to the Hilal visibility. Unlike other astronomical events such as eclipses whose forecasts since ancient times coincide with the event itself, determine Hilal according to the criteria of Islamic jurisprudence has always been a complex subject.

Second point: In addition to disrupting the accuracy of forecasts of Hilal and its visibility, this complexity prevents to paying attention to individual (and not collective) observations of Hilal especially in times and places where visibility of Hilal was impossible.

Third point: Add to this, the political gesture of some countries to be at the forefront of the Islamic scene, as it has always been in the history. This fast is an impediment to the scientific and religious transparency about Hilal.

Forth point : As in religion there is no difficulty, the Islamic law and the ritual of the Truth, in this precise case like all other cases of religious law recommends the easier methods. At Sunset of the 29th day of each lunar month, the Shariah prescribe to the believers that they try to see the Hilal. If the Hilal has been observed collectively (not individually) and when there was no impediments to the observation, the first day of the month is declared. If the Hilal haven’t be seen, so the month has thirtieth day.

Fifth point: : When there is disagreement about Hilal observation between Muslims, the Custodians of the Revelation (aleyhimo s-salam), have guided the followers of the Truth to very precise and easy scientific rules that if the believers apply them, without any worry, they can easily identify the first day of the month. astronomical Research Institute (in astronomical and astrological calendar) of Hayaat-aĕlaa Fondation has calculated the first day of every month and has extracted different types of astronomical calendars (universal – professional - concise) based on the directives transmitted by the Discourse of Revelation (aleyhimo s-salam).  

1- Between astronomical objects and virtual planets and objects, there is about twenty different astronomical aspects such as conjunction, square, trine, sextile…. Every astronomical object has a radius and because of this radius, the astronomical aspects are limited in time. However, the beginning of the astrological aspect, its middle and decline until its end are registered and astrological rules related are formulated. The duration and the intensity of astronomical aspects are not always the same but astrological rules are general and applied in all cases.

 2- The Moon during its trajectory traverses different aspects whose the Conjunction. At this phase, the Moon is in taȟte šoãĕ (under the radiance) of the Sun and in this period it is the shadowed side of the Moon that we see from Earth. This phase is commonly called the interlunar days.

 3- In fact the Conjunction occurs at a specific time in the middle of this lunar phase but taȟte šoãĕ and interlunar days is the name of all the period including a time before and after the Conjunction. So in the morning of 27th (in incomplete months of 29 days) and in the morning of 28th (in full months of 30 days) at the moment of sunrise, the Hilal enter into taȟte šoãĕ of the Sun: this lunar phase is named interlunar days. In full months, this phase happens in the last three days of the month and in incomplete months, in the last two days. The Conjunction normally occurs in the middle of this period.

 4- The Moon in the continuation of its trajectory, when it comes out of taȟte šoãĕ (under the radiance) of the Sun) and interlunar days, the first time that Moon is seen, is known as Hilal and New Moon. The end of the interlunar phases and the apparition of the Hilal in incomplete months happen after sunset on the 29th and in full months after sunset on the 30th.

 5- In ancient astronomy and generally in the Oriental, Babylonian and Greek schoolhouses and also in the terminology of Islamic law, all the time that the Moon is in taȟte šoãĕ (under the radiance)of the Sun, this phase have this name (the Moon in taȟte šoãĕ) and is considered to be a part of the previous month. The new month starts only when the Moon comes out of this phase and the Hilal appears.

 6 - In the recent years, due to the development of the communications and public access to data of various astronomical centers in the world, especially occidental modern astronomical centers, some similar but different expressions causes controversy or astonishment, confusion and misguidance of some Islamic Centers. So it is necessary to clarify those expressions one by one to counter any errors..

 7- One of those terms is the expression NEW MOON. One of those terms is the expression « New Moon ». In astronomy, the definition of this term does not match with the definition of this term in Islamic astronomy and jurisprudence. In occidental modern astronomy what is called « New Moon » is the moment of the Conjunction that occurs in the middle of interlunar days while the new Moon in itself appears several hours after the Conjunction when the Moon came out of interlunar days.

Numerous people and also Islamic centers of some countries use the New Moon schedules published by international astronomical centers for determining the new crescent (the Hilal) and declaring the beginning of the lunar month. They are in error because they consider the literal meaning of the expression failling to consider the difference between the definition of this expression in modern astronomy and its scientific definition in Islamic jurisprudence and ancient astronomy. Question: The calculations of the modern astronomy centers are very precise, why determining the new moon according to published timetables is inappropriate? Some people will think or say through ignorance: Today although the calculations in astronomy and previsions of the New Moon are extremely precise, the Islamic jurists remain uncertain and insist on the Hilal observation with naked eye! This reflection has gradually makes its way and generates the omission of Islamic legal principles of new Moon / new Crescent as a criterion to determine the beginning of the Islamic lunar months. Some others, as New Moon doesn’t correspond with the visibility of the Hilal, they have called into question the accuracy of the calculations of the modern astronomy scientific centers because those Centers announce the New Moon when it’s absolutely impossible! Another problem, the declarations of people who pretend to have seen the Hilal at a time scientifically impossible: this subject exist in countries like Saudi Arabia and the countries which are their followers. The New Moon’s time is the moment of Conjunction in the middle of interlunar phases. In ancient astronomy and according to the Eastern astronomy school and also in the Islamic law, the interlunar phases are entirely included in the previous month. According to religious law (in all branches of Islam) this lunar phase has never been divided in two part with the first part of it belong to previous month and the second part belong to the next lunar month such as Western astronomy school conceives it. The "New Moon" occurs at the Conjunction time in the middle of interlunar days, thus the Moon, in the remainder of its trajectory, needs time to completely comes out of this phase even though the phase of the Conjunction is exceeded. When the Moon reflects light again it is the birth of the Hilal and the beginning of the new lunar month. .

 8- According to the explanations given, it becomes clear that the use of the expression "the Hilal birth " for the New Moon, the Conjunction and the middle of the interlunar days is absolutely inappropriate. This expression inspires confusion such as: the Hilal is borned but it hasn’t been observed! In fact, in this phase the Hilal can not be born because as long as the Moon not came out of taȟte šoãĕ of the Sun, the Moon doesn’t reflect the light, so, it can’t be question of Hilal birth.

9- Another confounding term and misleading interpretation of it, is the expression "exit of interlunar days" at the Conjunction time. The Conjunction happens in the middle of the interlunar days. As explained above, it is clear that from Conjunction time until the Moon comes out of interlunar days, there is still a long time. So the expression "exit of interlunar days" generates misleading interpretations such as: the Moon now came out of interlunar phases and the New Moon is born… at a moment the Moon is still in taȟte šoãĕ of the Sun and can’t reflect sunlight.  

10- Another misleading interpretation the expression "The age of the Hilal " "considering the elapsed time from the middle of the Conjunction. This expression inspires confusion such as: the Hilal is born whereas the Moon is still in interlunar phases. As long as the Moon hasn’t come out of this phases, the Hilal can’t be born . Then the elapsed time from the Conjunction, at the middle of the interlunar days, until the first crescent can’t be counted in the age of the Hilal because this period corresponds to a time prior to the birth of the Hilal. So this period is an integral part of the interlunar days and also an integral part of the precedent lunar month.

11- Another common mistake: determining the time of the Conjunction or NEW MOON with geocentric orbit. For determinate the Moon position, between the method which use a reference system whose origin is the center of Earth (geocentric orbit) and the method which use a reference system whose origin is Earth's surface (topocentric coordinates), there is a significant difference. The system using the topocentric coordinates is in accordance with the perception and what the terrestrial observer can see at different moments of the lunar phases. Since the beginning and the end of interlunar days are based on perception and visibility criteria, the appropriate method is the one which using the topocentric coordinates. At the other the system using the geocentric orbit considers the inhabitants on the Earth as an imaginary observer in the center of the Earth and therefore announces the moment of the Conjunction or the NEW MOON at the same time for all the inhabitants of the Earth which is an impossible situation... The study of the beginning and the end of interlunar phases are generally based on sensory perception of the terrestrial observer on the Earth's surface. So Astronomical centers report this event according to topocentric coordinates and they use this method also for the position of the Moon and the observation of the Hilal. However the Conjunction, which happens in the center of interlunar days, is studied according to geocentric coordinates and this method considers virtually the terrestrial observer at the center of the Earth. But if the beginning and the end of the interlunar days are studied according to topocentric coordinates, the conjunction and the age of Hilal should be also.

 12- Another misleading expression : "« the Hilal set (instead of moonset) before sunset » " when the Moon is still in interlunar days: as long as that the Moon hasn't come out of this phase, it can be question of Hilal. This expression is causing misunderstand of some Islamic jurisprudence centers which estimate that the Hilal is borned; they consider that the Hilal instead of being born after the sunset is born before. They suppose that the Hilal appeared in the afternoon and set before sunset. In reality, this is not the Hilal set, but the moonset which is still in interlunar phases and still invisible. However, if the New Crescent Moon is observed before sunset, in general the Hilal is valid.

13- About all what has been stated previously: these remarks do not relate to the different methods or in the foundations but concern all currents of astronomy and Islamic jurisprudence. The authors of calendars or Hilal statements and the beginning of the month, must take in consideration those comments and be vigilant to not perpetuate the confusion among the centers of astronomy and Islamic jurisprudence centers. Otherwise the centers must be attentive to the meaning of the terms used to avoid erroneous conclusions based on an incorrect interpretation of these misleading expressions.

 On the drawing you can see: the Moon located in taȟte šoãĕ (under the radiation) of the Sun and interlunar phases.

The situation n°1 ؛ is when the Moon is in the center of interlunar phases, at the moment of the Conjunction that is also called New Moon in modern astronomy. In this period the Moon is completely in interlunar days ; it is in a position where it can’t reflect the light of the Sun. As long as the Moon hasn't come out of this phase, the birth of the Hilal can not occur.

The situation n°2 ؛ is the continuation of the Moon trajectory in interlunar days; a time after the Conjunction and New Moon, the Moon can not reflect the light. Thus, the birth of the Hilal is still impossible.

The situation n°3 ؛ the Moon is beginning to coming out of the interlunar phases and moonlight is again visible. This moment marks the birth of the Hilal and its apparition.

About the Hilal rise and its visibility, many information should be considered whose time of sunset and moonset, the angle, the azimuth and the altitude of the Moon and the Sun, the difference between the two azimuths, Hilal’s age, how long the Hilal stayed in the sky at sunset, the longitude and latitude of observation zone… In the following of this article, it will be used some drawings to remember and also clarify some points and more specifically: the azimuths difference that is to say the difference of angular measurements, on the reference horizontal plane, between the position of Hilal when rose and the position of Sun when has set. and the maximum angle of the Hilal - relative to the horizon - at sunrise time that is to say the altitude of Moon at this time.

The following explanatory drawing is about the visibility of the Hilal at the moment of sunset in the first night of the lunar month. At the moment of sunset, the Sun reaches the altitude zero. In the drawing, the Sun has set (=zero degree) and the possibilities of Hilal visibility have been explored according to the altitude and the azimuth of the Moon: unobservable, visible, observable with powerful optical instruments, observable with common optical instruments or observable with naked eye. The hypothetical trajectories the Moon are signaled with different colors. If, at the time of sunset, the difference between the azimuth and the altitude of the Hilal reaches to the red line or lower, it is not possible to see the Hilal,  the red line is at an altitude of 5.5 degrees. In this situation the elongation is less than 7 degrees. Now, when the elongation is less than 7 degrees – this position is called “Danjon limit”, the Moon is completely invisible.

If, at the time of sunset, the maximum difference between the azimuth and the altitude of the Hilal reaches to the orange line, it is extremely difficult to see the Hilal If, at the time of sunset, the maximum difference between the azimuth and the altitude of the Hilal reaches to the green line, it is difficult to see the Hilal If, at the time of sunset, the maximum difference between the azimuth and the altitude of the Hilal reaches to the yellow line, there is a possibility to see the Hilal . If, at the time of sunset, the maximum difference between the azimuth and the altitude of the Hilal reaches to the purple line, it is highly likely to see the Hilal ، If, at the time of sunset, the maximum difference between the azimuth and the altitude of the Hilal reaches to the blue line, the observation is easily.

The gray line that has been drawn to the center of the Hilal shows the trajectory of the Moon until the Moon set. This trajectory changes in different months because of the complexity of the Moon’s moves and its orbit. The gray line that has been drawn to the center of the Hilal shows the trajectory of the Moon until the Moon set. This trajectory changes in different months because of the complexity of the Moon’s moves and its orbit.

This drawing about the visibility of the Hilal is published before the beginning of every lunar month in «The monthly of the Hilal» and also in the publication called «Hengaam-shenaasi ». To view these publications:

http://Aelaa.Net ( The site of Hayaat- aĕlaa )

http://Aelaa.Net/Tal/En/1.aspx ( The site of Hayaat-aĕlaa Fondation )

http://Aelaa.Net/Tal/En/Nojum.aspx ( The site of the Circle of astronomy and astrology - Daar al-Maĕaaref al-Ilaahiyyah )

And to view the previously published publications, refer to following Internet address:

http://aelaa.net/Fa/viewtopic.php?f=52&t=27&sid

 
Most of the Foundation Hayaat-aĕlaa’s calendars are lunar, but as the people need to make the link between the different Moon’s shapes and the days of lunar months in the solar calendar, the Foundation is publishing a solar calendar with the exact Moon’s shape for every day of lunar months. This calendar is based on a solar count of years and months but it focuses on the Moon’s phases and the description of its shape for every day of the lunar months. Therefor this calendar was been named: Moon Phases Solar Calendar = Daily description of lunar phases for every months of solar year. This calendar is published since 5 years.