Whilst there is universal agreement that at 18 degrees of solar depression no trace of light remains in the night sky, there is considerable objection to adopting 18 degrees as the correct angle for Subha and Isha, in the light of the definitions provided by the Quran and Hadith.

The Holy Quran is quite clear about when dawn begins:

“..and eat and drink until the white thread of dawn appears to you distinctly from the black thread”


Let us examine in this paper whether or not 18 degrees matches up to this definition.

‘Astronomical Twilight’ which is the term given for the condition of the night sky during 12-18 degrees is defined by the US Naval Observatory as,

“Before the beginning of astronomical twilight in the morning and after the end of astronomical twilight in the evening the sun does not contribute to sky illumination; for a considerable interval after the beginning of morning twilight and before the end of evening twilight, sky illumination is so faint that it is practically imperceptible”

This definition rules out the description in the Quran of Subha. At 18 degrees sky illumination is so faint as to render it ‘practically imperceptible’. 18 degrees cannot therefore be used as the starting time of Fajar as the Shariah requires the white thread of dawn to be distinct from the black thread of night.  

To establish Subha the light of dawn needs to spread along the width of the horizon and be noticeable by the naked eye. This is not the case at 18 degrees when there are only traces of scattered light which is hardly noticeable without the use of instruments and does not resemble a broad light across the width of the horizon.

“…the way the human eye detects light flux, which is subsequently registered by the brain, is different from that of a general light detector. Besides, the theological defining system for Fajar (and Isha) is dependent upon a certain observed phenomenon- a whitish envelope of about 30 degree width above the eastern horizon”

(M.Ilyas, Astronomy of Islamic Times for the Twenty First Century)

G.V. Rozenberg, a renowned expert on twilight states,

“During this period the illumination conditions can hardly be distinguished from night”

(G.V.Rozenberg, Twilight: a study in atmospheric optics)

Let me be absolutely clear what ‘period of illumination’ Rozenberg is referring to. Rozenberg refers to Astronomical Twilight which he, like all astronomers, considers being between 12-18 degrees and not fixed at 18 degrees only. So the condition of the night sky during this period is for all practical purposes that of night time. Not AT 18 degrees but FROM 12 degrees to 18 degrees.

Astronomers also to refer to an earlier phase of illumination which is ‘Nautical Twilight’ which is the term given to the condition of the night sky from 6-12 degrees and the end or beginning time (ie 12 degrees) is described by the Royal Greenwich Observatory as,

“Dark for all normal practical purposes and the sea horizon is not normally visible”

(RGO Information Sheet no 7)

Nautical Twilight is known as nautical twilight because this is the time when it is too dark to see ships approaching harbour. This is why the term was invented to provide ships sailing the sea some idea of when they will be spotted without the use of artificial lighting.

“At the beginning or end of nautical twilight….the horizon is indistinct”

(US Naval Observatory)

Dr Steve Bell the most senior astronomer at the RGO replied to an enquirer in February 1994 confirming that at 12 degrees the horizon would not be visible, just like it would not be visible at 15 and 18 degrees,

“….at depressions of the sun of 15 degrees and 18 degrees, the horizon would not be visible. At depressions of less than 12 degrees the horizon would just be visible”

(Dr Steve Bell, Royal Greenwich Observatory)


See also what the RGO Information Sheet No. 7 says about defining dawn or determining the time of first light,

“There is no precise definition of ‘dawn’, if it is interpreted as the time of ‘first light’, dawn corresponds to a depression between 18 and 12 degrees but it is not possible to be more precise”

(Yallop & Hohenkerk)

This is what Dr Omar Afzal, Shaukat and Imam in their paper “When to pray Fajar and Isha” have said,

“The change in illumination from 13 to 18 degrees is so negligible that, without instruments that were only available from the 1940’s, the change would not make any appreciable difference to the naked eye”

(Afzal, Shaukat & Imam, When to pray Fajar and Isha)

What is absolutely clear from astronomers is that 18 degrees is practically night time for the general populace. It is only for practising astronomers that it is an issue as before 18 degrees the traces of light in the sky results in hindering astronomical observations. As Astronomical Twilight begins at 12 degrees and ends at 18, astronomers can start to observe the night sky from 12 degrees but will find difficulties with their observations, the best time for them to observe is after 18 degrees when no trace of light exists.

Professor Abdul Haq Sultan of Sana’a University in Yemen has carried out extensive studies into this issue and concludes that 12 degrees is the appropriate angle for Subha Sadiq,

Fajr Time: It starts with the true dawn (the beginning of nautical twilight) when the sun’s altitude is -12 degrees”

(Abdul Haq Sultan, Suns apparent motions and Salat time)

This explains why first generation scholars who arrived in this Country several decades ago adopted 12 degrees as the correct angle after considering the definitions provided by the Observatory at the time. In fact many scholars such as Molana Manzoorul Haq (RA) of Birmingham tested this by observations and were satisfied that 12 degrees was the correct angle. It was not until much later that pressure to adopt higher values such as 18 and 15 degrees were brought to bear resulting in many Masajid abandoning 12 degrees.
This pressure which remains strong today is based purely on the scientific definition provided for 18 degrees, at the end time of which, admittedly, there is still some trace of light in the night sky but this illumination is hardly noticeable to the naked eye and only enters the definition because it hinders astronomical observations, hence it is referred to as Astronomical Twilight.

Does this mean Hizbul Ulama UK is advocating Subha Sadiq at 12 degrees?

No it does not, what we are saying is that when all indications from experts point to a possibility of Subha Sadiq being at 12 degrees how can Subha Sadiq be at 18 Degrees?

Hizbul Ulama’s stance is quite clear on this issue. Our research shows that as a measurement solar depression angles are only a general guide and do not fulfil the requirements set by shariah. Solar depression angles are intended to measure the level at which the sun is at a given time and proves useful for sunset, sunrise, and zohar which are related to the position of the sun. The twilight prayers of Fajar and Isha on the other hand rely on sky illumination, as confirmed by Professor Ilyas,

“The situation of twilight phenomena is different from the sunset and sunrise phenomena because in the former case it is not the position of the sun but the light of the evening sky which we are primarily interested in”

(Professor Ilyas, Astronomy of Islamic Times for the Twenty First Century)

In terms of using solar depression angles to precisely fix our prayer times for Fajar and Isha, as already mentioned, degrees may be convenient but not necessarily appropriate as they are only general classifications, and may give imprecise timings,

“Before sunrise and again after sunset there are intervals of time, twilight, during which there is natural light provided by the upper atmosphere…it is possible to establish useful, though necessarily approximate, limits applicable to large classes of activities considering only the position of the sun below the local horizon”

(US Naval Observatory)

We have carried out extensive observations in Blackburn Lancashire during 1987-88 which suggests that Subha Sadiq fluctuates between 12-16 degrees in the UK. Many other observations carried out in various parts of the world fall within a similar parameter.


Dr Khalid Shaukat of moonsighting.com states,

“The phenomenon of Subha Sadiq will vary in degrees at different latitudes and different seasons, because of the sun travelling (apparently) along a specific latitude on a specific date. The sun (apparently) travels between Tropic of Cancer and Tropic of Capricorn in different seasons. People in different locations around the globe have made observations about Subha Sadiq and the results are anywhere between 13.5 degrees to 18 degrees”


So latitude and seasons make a difference in sky illumination conditions.

“Latitude makes a big difference in the duration of sunset effects. At the rising and setting points of the sun the diurnal path is tilted with respect to the vertical by the angle of the latitude of the observer. At the equator this angle is zero, and the sun plunges quickly below the horizon because the solar altitude is decreasing at its greatest rate. At high latitudes this angle becomes large, and the sun sets more slowly because the solar altitude is decreasing slowly. This makes twilight pass into night rapidly in the tropics and slowly in high latitudes, even though the sun moves along it diurnal path at essentially the same rate”

(A&M Meinel, Sunsets, Twilight and Evening Skies)

Professor Ilyas acknowledges this in his work,

“…there seems to be some room for geographical variability and perhaps 18 degrees serves as an upper limit only…..sine the term Astronomical Twilight has been reserved for the instant when the solar depression at the surface horizon is 18 degrees, it is necessary to introduce a separate term which relates to the beginning of Isha and Fajar and which can be assigned, if necessary, different solar depression values, depending upon the geographical location and other considerations”

(M. Ilyas, Astronomy of Islamic Times for the Twenty First Century)

It is understood that fluctuations in tropical countries is rather less than in countries in non tropical countries.

Like the Hizbul Ulama observations many observations carried out in other parts of the world reveal that 18 degrees is not correct. 

In the USA a team in Chicago found via observations made in 1985 that Subha Sadiq fell between 13 and 15 degrees. Other observations in the US show that it occurred around 12 degrees. Observations in Toronto, Buffalo, Montreal, San Francisco, Tempe, Houston, and Washington DC also confirm 13 to 15 degrees. In Eastern Australia observations equated to 13/14 degrees.

Hizbul Ulama has recently been contacted by a group in Belgium who have found through observations that their timetables based on 18 degrees were incorrect. Unfortunately the mosque Committee at the time of writing has ignored their plea to alter their timetable and the brothers are desperate to convince people in Belgium that the timetables they are using are incorrect.

Sheikh Muhammad Salih Al-Munajjid (Islam Q&A website) has cautioned against timetables based on 18/19 degrees,

“This mistake does not occur only in Egypt, rather it seems that most of the timetables do not give the correct time for Fajr and are based on the false dawn. This means that there is the risk that the Muslims’ prayers are invalid, especially in the case of those who pray in their homes immediately after hearing the adhaan.

A group of scholars and researchers in the Kingdom of Saudi Arabia, Syria, Egypt and Sudan have attempted to find out the time of the true dawn and it is clear to them that the timetables in use at present are incorrect.

Shaykh Albani (RA) said:

‘I have seen that myself many times in my house, in the Hamlaan mountains to the south east of Ammaan, and that enables me to confirm what some of those who are keen that the Muslims’ worship should be correct have said, that the adhaan of Fajar in some Arab countries is given 20-30 minutes before the time of the true dawn’

(Shaikh Albanni, Al Silsilah Al-Saheehah, 5/25)


This is also precisely what Shaikh Ludhyanvi (RA) and Mufti Safi’ (RA) found with Pakistan timetables after carrying out their own observations and cautioned people to wait 20-30 minutes before performing their Fajar prayers.

Mufti Ludhyanvi (RA) explains in graphic detail his observations which include the Milky Way galaxy and the effect of the Seven Stars constellation on the night sky. Mufti Sab also observed the zodiacal light. Mufti Sab issued a Fatwa based on these observations,

“The time of Subha Sadiq, given in the charts based on 18 degrees, and in common use in Karachi is undoubtedly not of the real Subha Sadiq. It is probably the time of Subha Kadhib, and given as an extreme precaution for the Muslims to stop Suhur in Ramadhan….therefore the time given in these charts are incorrect. If adhan is called at least 20 minutes later and Fajar Salat held after this, then it will be correct and valid in all seasons”

(Mufti R.A.Ludhyanvi, Subha Sadiq, Ahsanul Fatawa, Volume 2)

Mufti Shafi’ (RA) ruled similarly,

“This fact is undisputable that the use of 18 degrees in timetables for Subha Sadiq is not of the true Subha Sadiq but possibly of Subha Kadhib, which is probably used for the end of the fast due to safety reasons….therefore those men and women who perform their Fajar prayer immediately after the 18 degree beginning time are wrong to do so”

(Mufti Shafi’, Ahsanul Fatawa)

Despite such high levels of confidence by both scholars in their observations and so much self assurance in their ruling against the use of 18 degrees, Pakistan reverted to using 18 degrees due to the influence of Professor Latiff who carried out seven observations confirming 18 degrees. Dr Omar Afzal et al are however highly critical of the assumptions made by Latiff to back the use of 18 degrees and the apparent disregard of his own findings.

Professor Ilyas who has carried out extensive studies of his own on the topic of twilight points to observational studies suggesting values up to 16 degrees which back up his own study of flux conditions,

“We find that the flux decreases rapidly until about 16 degrees and then the change is rather small, although with an optical detector a small change such as the one between 16 and 18 degrees can be recorded, it may not make an appreciable difference to the human eye…..Besides the use of smaller values up to 16 degrees in certain Middle East countries which we mentioned, preliminary results from a recent observation study also indicates this to be so”

(M. Ilyas, Astronomy of Islamic Times for the Twenty First Century)


The conclusion of this paper is that expert opinion as well as naked eye observations points very strongly to the rejection of 18 degrees, in fact also the rejection of any angle without careful verification through observations.

Even the use of 15 degrees is questionable as observations show that there is fluctuation throughout the year particularly in countries in the northern latitudes. Fixing one angle is therefore folly and must be avoided if we are to perform our Ibadaah at the correct times.

Full details are available on this subject in the book, Fajar and Isha Times and Twilight, published by Hizbul Ulama UK and available to download from its website:


Y.A. Miftahi