Moon SightingBetween Science and Religion

Dr. Hussein Mhanna

Constant Controversy• Causes? • Scientific or religious?• Can we find a unifying solution?• Or is it natural to have this controversy?

The Moon’s motion• Fastest cosmic

object in our sky: crosses 13 degrees daily(compared to 1 degree by the Sun daily)• The Moon takes 27.3

days to orbit Earth, but the lunar phase cycle (from new Moon to new Moon) is 29.5 days.

The Moon Phases

The Moon Cycle

Conditions for Crescent Visibility

• Birth of New Moon• Illumination of the moon• Duration after sunset• Elevation above the horizon

1. New Moon Birth

• At the end of a lunar month the Moon passes between the Earth and the Sun;

• This moment is called "New Moon Birth" or conjunction. • At this moment the sunlight falling on the moon cannot

come to the earth. In other words new moon is "No Moon".

• No one can see this "New Moon" even by most powerful telescopes.

• The conjunction can occur at any time between 24 hours.

2. Illumination of the moon

• In order for the bright (illuminated) side of the moon to be visible to an observer on earth, the angular distance between the moon and the sun needs to reach a certain value.

• This distance is called:Moon’s elongation

Moon’s Elongation

• Is the apparent distance between the moon and the sun in the horizon.

• From the birth of the new moon forward, this distance increases until it reaches a degree where the bright side of the moon becomes visible as a crescent.

• Elongation is measured in degrees.• Each degree = 2 hours of the moon’s age.

Elongation required for Visibility

• No consensus between scientists• In ancient times, scientists considered 12

degrees as the minimum requirement• Later scientists moved it to 10 degrees• Recent scientists moved it down to 8

degrees, with a possible visibility at 7 degrees.

3. Duration after sunset

• The time difference between sunset and moonset.

• How long the moon stays above the horizon after sunset.

• So if the sun set at 6:00 p.m. and the moon set at 6:30 p.m., the moon’s duration after sunset is 30 minutes.

Duration required for Visibility

• A certain time must pass after sunset for the crescent to be visible.

• The horizon is too bright right after sunset that it overcomes the faint light of the small crescent, which makes it very difficult to spot.

• The longer the crescent stays above the horizon after sunset, the greater the possibility for visibility.

• No consensus on the required duration.

4. Elevation of the Moon

• It’s the height of the moon above the horizon.

• The higher the moon, the further it is from the bright horizon, the greater the possibility for visibility.

• It is measured in degrees.• No consensus on the required degree.• Opinions vary between 4, 5 and 6.

مسا 06:31:13ًء1

غروب الشمس

مس  06:38:27اًء1

القمر غروب

ث14د 07س 0 المكث

8.785° االستطاله

0.611° االرتفاع

يسار   8.649°الشمس

القمر بعدأفقيا1

0.44% االضاًءة

د 49س 16ث19

القمر عمر

شبه مستحيلة مستحيلة)

)1 عمليا

إمكانية الرؤية

جدول اإلستهالل في منطقة

القطيف

مساًء1 06:30:40 غروب الشمس

مساًء1 07:15:35 القمر غروب

ث55د 44س 0 المكث

°18.545 االستطالة

°8.731 االرتفاع

يسار °15.884الشمس

القمر بعدأفقيا1

2.60% اإلضاًءة

ث46د 48س 40 القمر عمر

ممكنة  الرؤية إمكانية

جدول اإلستهالل في منطقة

القطيف

• Ignoring local conditions for the moment and visualizing the problem from outside the Earth's atmosphere, the size and brightness of the lunar crescent depend on only one astronomical quantity: the elongation of the Moon from the Sun, which is the apparent angular distance between their centers. For this reason, the elongation has also been called the arc of light.

• If the value of the elongation at any instant is known, the width of the crescent can be computed.

Additional Factors

• The elongation as a function of the Moon's age depends on several factors:

• The Moon's elongation at New Moon• The speed of the Moon in its orbit• The distance of the Moon• The observer's location

Test your knowledge

True or False:• Distance between the moon and Earth is

constant?• Speed of the moon is constant?• Orbit of the moon is circular?

The Moon's elongation at New Moon

• The elongation of the Moon at New Moon is not necessarily 0. The Moon's center may pass directly in front of the Sun at New Moon (when a solar eclipse will occur) or it may be as much as five degrees to the north or south of the Sun. That is, the Moon can start the month with an elongation ranging from zero to 5 degrees.

The speed of the Moon in its orbit

• The Moon's orbit is elliptical, and its speed is greatest when it is near perigee (closest to the Earth), least near apogee (furthest from the Earth).

• If perigee occurs near New Moon, the Moon will appear to be moving away from the Sun in the sky at a greater than average rate.

The distance of the Moon

• Because of its elliptical orbit, the distance of the Moon varies. Even if the Moon moved with a constant speed, its angular motion as viewed from the Earth would be greater when the Moon is near perigee. Similarly, a nearby automobile appears to be moving quicker than a more distant one, even if they are actually moving at the same speed.

• The combined effect of these factors gives geocentric elongation of the Moon from the Sun at an age of one day can vary between about 10 and 15 degrees.

• This large range of possible elongations in the one-day-old Moon is critical.

• The prediction of the first sighting of the early crescent Moon is an interesting problem because it simultaneously involves a number of highly non-linear effects.

• Stated in less technical language, many things are changing very rapidly.

Effects to be considered

• The geometry of the Sun, Moon, and natural horizon

• The width and surface brightness of the crescent

• The absorption of moonlight and the scattering of sunlight in the Earth's atmosphere

• The physiology of human vision.

A logical question

• With all the scientific advancements that we have, why can’t we find a solution?

An unexpected answer!• Despite all the technology we have,

modern science hasn’t been able to put accurate criteria for moon sighting.• The motion of the Moon differs from

that of the Sun.• This peculiarity limits our ability to

apply accurate early predictions

• Although the date and time of each New Moon can be computed exactly, the visibility of the lunar crescent as a function of the Moon's "age"—the time counted from New Moon—depends upon many factors and cannot be predicted with certainty.

Source: The Astronomical Applications Department of the U.S. Naval Observatoryhttp://aa.usno.navy.mil/faq/docs/crescent.php

Visibility Maps

Visibility Maps

• Visibility maps are made according to criteria developed by scientists.

• Oldest known criteria were developed by the Babylonians.

• Many criteria were developed after that.• Most used criteria nowadays is Yallop's.

How accurate are these maps?

• Several examples in recent history showed that visibility maps are not accurate enough.

• There were years when visibility was not possible according to the maps, yet the crescent was sighted.

• And years where maps predicted easy visibility yet no crescent was sighted despite perfect conditions.

• Most recent example: Eid Al-Fetr 1435

As you can see from this map for Shawwal 1435 AH, the crescent of eid Al-Fetr was supposed to be “visible with the naked eye under perfect conditions” in south America, however there were no confirmed sightings of the crescent that night.

Conclusion

• Visibility maps, and astrological calculations cannot be used as a sole basis for determining the beginning of lunar months.

• They can only be used as a guide for moon-sighting.

Big Moon (must be 2nd day moon?)

• In order for a crescent to be visible, the moon has to at least about 16 hours old.

• Imagine 2 situations: Situation 1 Situation 2

Age of the moon at Sunset 16 hours 15 hours

Crescent Visible Yes No

Age on the next day 16+24 = 40 15+24 = 39

Result

• It’s clear that a crescent 40 hours old and another 39 hours old will look almost the same size to the naked eye.

• Yet the 1st crescent is a 2nd day moon.• Whereas the 2nd one is still the 1st day of the

month.

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& ا ُأ �اُن& م&ْر�يَض�� و&م&َن َك��&�ُم� �ُك �ْر�ي�د� َب & ي ْر& و&َال �ْس�# #ي �ُم� ال �ُك �ْر�ي�د� ا�لل�<ِه� َب ْر�& ي �َخ�& 3 ُأ &ي��اٍم د�ٌةA م�َن# ُأ� ف&ِع���ُم# د&اَك ا ُه�& ِه& َع&ل&ى م�& # الل�< وا ْر� �&ِّب� �ُك �ت د�ٌة& �و&ل #ِع�� # ال وا #ِم�ل�� �ُك �ت ْر& و&ل #ِع�ْس�# ال

وُن&{ )� �ْر� ُك &ْش# �ُم# َت �ُك &ِع�&ل ( سوَرٌة الِّبقْر�ٌة185و&ل• The month of Ramadhan [is that] in which was revealed the Qur'an, a

guidance for the people and clear proofs of guidance and criterion. So whoever sights [the new moon of] the month, let him fast it; and whoever is ill or on a journey - then an equal number of other days. Allah intends for you ease and does not intend for you hardship and [wants] for you to complete the period and to glorify Allah for that [to] which He has guided you; and perhaps you will be grateful.

2 key words in the verse

1. aد bِه aش which means: sights2. aر gِه hالش which means: monthThe 1st word “sights” clearly denotes “eyes” not “calculations”.The 2nd word as translated to “month”, doesn’t make sense in the context of the verse, how can some one see a “month”… so what does it mean?!• Why didn’t Allah just use the word “moon”, or

“crescent”?! Instead he used a word that is usually translated as “month”.

Why the Quran used: “Month”

• The Arabic word used “ aر gِه hالش” has a common origin as the word “ aر aِه aش” which means “to make well-known/famous/renowned”.

• So it seems now that Allah wanted the month of Ramadhan to start with a crescent that is well-known/famous/renowned.

• In other words, a crescent that can easily be seen by everyone, not just those with extraordinary eyes, or with complicated equipment. The following hadith makes it more clear…

Hadith

قال اإلمام جعفر الُصادق (ع): فال تddؤدوا إن شddِهر رمضddان فريضddة من فddرائض اللddه

بالتظني!وليس رؤيdة الِهالل ان يقdوم عdدة فيقdول واحdد قdد رأيتdه

إذاd رآه واحdد رآه dمئdة وإذاd رآه مئdة ويقdوdل dاآلخdروdن لُمd dنdره رآه ألف

Imam As-Sadeq said: The month of Ramadhan is a religious obligation/duty from Allah, so do NOT perform (fasting) based on assumptions! And moonsighting is not when one person comes and says “I saw it” whereas others say “We didn’t”. If one sees it, a hundred should be able to see it as well, and if a hundred can see it, a thousand should be able to see it.

Another hadith

قال اإلمام محمد الباقر (ع): إذا رأيتُم الِهالل فُصوموا وإذا رأيتموه فافطروا

وليس هو بالرأي وال بالتظني ولكن بالرؤية

Imam Al-Baqer also spoke about this issue:“If you saw the crescent moon (at the beginning of Ramadhan) then start fasting, and if you saw it (at the end of the month), then break your fast (observe eid), and it is not by personal opinion nor by assumption, but by sighting!

Question to ponder on

• Is this science of astrological calculations new?• Weren’t the ancient Chinese astrologists

experts in this science thousands of years before Islam?!

• Didn’t the Prophet and Imams know about it?• Did they use it?• If not, why?

• It’s clear that the Prophet (PBUH) depended only on eye-sighting of the crescent.

• It’s known now that the visibility of the new crescent starts in the western parts of the world (North America in winter, and South America in summer), and that’s why people in the west very often see the crescent a day or two before it becomes visible to the people in the east.

• So if there were Muslims in the time of the Prophet living in the Americas, they would have started the lunar month at least one day before the Prophet and the Muslims of the Medina, since they could see the crescent earlier.

• So if the rule is that month must start based not on sighting but on knowledge that the crescent can be sighted anywhere in the world (calculations), shouldn’t the Prophet have made these calculations? Or even easier than that, wasn’t he able to get the “news” of moon sighting in the west from Allah through the angel Gebrail?!

Hilal of Ramadhan 1436

وُأنتُم َبخيْرَكل َعاٍم

Sources• www.kitabati.net/subject.php?id=22• www.qanaa.net/?id=36• http://www.sh-omair.com/• Wikipedia• www.crescentwatch.org• www.islamicmoon.com• www.moonsighting.com/faq_ms.html• http://aa.usno.navy.mil/faq/docs/crescent.php• www.staff.science.uu.nl/~gent0113/islam/

islam_lunvis.htm• www.shiaonlinelibrary.com• www.Quran.com• http://www.sistani.org/arabic/qa/0483/