بِسْم الله الرحمن الرحيم
The Arabic noun Maghrib comes from the root gharaba, “to depart, to set, to go away,” and the noun formed from this root literally means “the place of the sunset.” It is thus apparent that Maghrib means actual sunset or sundown, as understood universally, i.e, the time of departure or declension of the sun from the horizon when it is no longer visible.
The Maghrib Prayer
The exact timing of this prayer has reached us in great detail due to the rules regarding the break of the fast at Maghrib, or sunset. The Prophet ﷺ informs us thus,
“When night falls from this side and the day goes from this side and the sun disappears, you should then break your fast.”[Tirmidhi]
Thus, the scholars have concluded that the start of Maghrib, and by extension the end of the fast, will occur when the disk of the Sun has disappeared below the horizon even if there is some light still visible in the atmosphere.
So what then is the point of this article, one may wonder, as what has been mentioned above is surely accepted and followed by all without question. The point, however, is that there is a slight difference to how we calculate our times and how the times were originally recognised.
In the hadith quoted earlier, it is evident that what was performed was a visible recognition of a celestial occurrence. In arabic, the word used often in the hadith is Ru’yah, “to see”, such as when the hadith says “soomu li ru’yathih“, fast when you see it (new moon).
Whether it is the distinction between the black thread of dawn from the white thread, or the sighting of the moon, or our dependence on earth (tayammum) and water (wudhu) for spiritual purity, what is apparent is that we are tied to nature intimately, both passively and actively, and this personal involvement with nature is commanded throughout the Qur’an such as when Allah Almighty tells us,
“Verily! In The creation of the heavens and the earth, and in the alternation of night and day, there are indeed signs for men of understanding. Those who remember Allah standing and sitting and lying on their sides and reflect on the creation of the heavens and the earth: Our Lord! Thou hast not created this in vain! Glory be to Thee; save us then from the chastisement of the fire.” [Qur’an: 3:191]
Apparent and Actual Sunsets
This visible phenomenon, however, belies its apparent simplicity. Sunet times can be computed easily for any geolocation, however, there is one small issue; the calculations assume a perfect line of sight without air pressure, atmospheric refraction, and air pollution. When we add these variables into the equation, then it seems several additional minutes are required.
Going back to what was mentioned earlier, it can be noted that we fast and we pray and we break our fasts with a visible celestial or geological phenomena. When we cannot observe said phenomena, then we must calculate the time of the actual observance and not of the actual occurrence.
This brings us to the title of the article; apparent sunset.
Astronomically, there are two sunsets; apparent, and actual.
Actual sunset is the exact moment in time the disk of the Sun descends below the horizon of a given location on Earth.
Apparent sunset is the time the observer witnesses the above.
The reason why there is a time disparity is due to light refraction as well as on a smaller scale, air pressure and pollution.
When light passes from one medium (material) to another, it changes speed. This is because the speed of a light wave is determined by the medium through which it is passing. This change in speed causes the light to bend (refract) and it is a well known and observed phenomenon. Observable refraction is demonstrated in the following picture.
As light from the sun (or another celestial body) travels from the vacuum of space into Earth’s atmosphere, the path of the light is bent due to refraction. This causes stars and planets near the horizon to appear higher in the sky than they actually are, and explains how the sun can still be visible after it has physically passed beyond the horizon at sunset.
Pollution within our atmosphere further affects the refraction of light 1 . and is different at various places on Earth. In addition to pollution, the extent of the refraction also depends on atmospheric turbulence, including air temperature and atmospheric pressure: the higher the pressure and the lower the temperature, the larger the refraction angle.
If you witness the sun set in an area of high pressure on a cold day, you may have to wait several seconds for the upper edge of the sun to disappear behind the horizon, compared to a day with average pressure and temperature 2. Although pollution may have an impact on refraction, turbulence in the Earth’s atmosphere has a much higher impact on refraction of light, particularly temperature variations in the atmosphere. 3
In conclusion, when it comes to sunset for the establishment of Maghrib time and by extension, the time of Iftar, one has to account for atmospheric refraction because the physical sun is actually lower than what appears to our eyes. 4
Previous Four Minutes Recommendation
The phenomenon of sunrise/sunset times not being consistent with the naked eye was first raised in the 1990s. In a research paper by Dr Bradley E. Schaefer (1990) 5 he explicitly stated that,
“The time of sunrise can only be predicted with an accuracy of four [minutes]”,
and sunset times may also suffer from inaccuracies. Science is driven by observations and research and in 2018, we have more precise observational data for high latitude countries.
Certain timetables and calculation algorithms already account for this refraction to a certain degree. Take for example, the widely used Her Majesty’s Nautical Almanac Office (HMNAO).
HMNAO data sheet (7) states:
The sunrise and sunset times that are prepared by Her Majesty’s Nautical Almanac Office correspond to the instants times when the zenith distance of the centre of the Sun is 90° 50 ́: this allows 34 ́ for refraction in the atmosphere and 16 ́ for the angular semi-diameter of the Sun. (The zenith distance of an object is the angle between the direction to the zenith (i.e. the point vertically overhead) and the direction to that object.) 6
Our Sun Calculator, which shows sunrise and sunset times in a location of your choice, takes the effect of refraction into account. Our calculations are based on the standard atmospheric pressure of 101.325 kilopascals and temperature of 15°C or 59°F, so sunrise and sunset may happen some seconds before or after the stated time when the temperature or pressure strongly deviate from the average.
Here are the sunrise and sunset times for a location in Kidderminster, which is at 52° 23′ North and 2° 14′ West for 30th May 2018.
Statement from Wifaqul Ulama, UK
“While there are scientific studies on this topic from various regions around the world, there is no consensus on how refraction affects sunset times in (specific parts of) Britain. 7. Having said that, raw data from Alberta, Canada, has demonstrated a seasonal change in the observation of sunset with greater levels of refraction around winter compared to summer 8 When this refraction data is used in the U.K. setting we find the value varying from 4 minutes to 7 minutes. We appreciate this may not be wholly accurate due to the difference in setting, but until a similar study is conducted in U.K. we will utilise it; especially as it suggests a later time which is more precautionary when it comes to acts of worship. For instance, we can add that similar research carried out in Holetown, Barbados 9 found the refraction to be lower suggesting a further two minutes deducted from HMNAO would be sufficient. Returning to the Canadian data, once the two minutes which HMNAO deduct to take Astronomical refraction into consideration we are left with an additional 2 to 5 minutes. We have consulted two experts in this field and their opinions have differed on the matter. Therefore to take seasonal effects into consideration and to be as precautionary as possible without increasing the time unnecessarily, also to issue a standard value for the year we recommend adding five minutes to the HMNAO time for sunset. We have confidence from those astronomers that we have consulted that we will be well within the correct timeframe. This is an ongoing research pursuit for Wifaqul Ulama and more research will be presented in due course.”
The Sunnah severely warns the Muslim who breaks his fast before sunset.
It was narrated on the authority of Abu Umamah Al-Bahili that the Prophet said: “Two men came to me, held my upper arm and we went to a rugged mountain. They asked me to climb it, but I told them I could not. They told me that they would make it easy for me. When I climbed the mountain and reached its middle, I heard loud voices. I asked, ‘What are these voices?’ They said, ‘This is the howling of the people of Hell.’ Then I was taken [to another place], and I saw people hanging from their hamstrings, with the corners of their mouths torn and dripping with blood. I asked, ‘Who are these?’ They said, ‘The people who broke their fast before the proper time of breaking the fast.'” [An-Nasa’i: Al-Kubra] [Al-Hakim said “Saheeh according to the conditions stipulated by Muslim” and Ath-Thahabi agreed with him]
Statements From Contemporary Scholars
Answered by Mufti Ebrahim Desai
A difference of opinion exists in our town regarding the exact time of Iftaar. Some are of the opinion that it is necessary to open fast immediately after sunset based on the Hadith of Bukhari that “people will continue in prosperity so long as they make Ta’jeel (be quick) in breaking the fast.” Others are of the opinion that as a matter of precaution, the fast should be opened a few minutes after actual sunset, as the time in the Muazzin’s clock or the perpetual timetable, may not be absolutely correct. Kindly comment.
The Fuqahaa have stated that it is Waajib to exercise precaution in breaking fast. (Tahtaawi; Karachi pg.370). Ibn Nujaym states, “Ta’jeel (to be quick) which is desired in breaking fast is before the stars appear” (Bahrur Raaiq vol.4 pg.292) In view of the above, it is not necessary to break fast immediately after sunset in order to achieve the virtue mentioned in the Hadith. The virtue will still be achieved even though there is a slight delay.
The Hadith of Bukhari referred to in your questionnaire is explained by Ibn Hajr (Rahmatullaahi Alayhi) in Fathul Baari (vol.4 pg.191) as follows: “The Christians and Jews used to delay their fast until the stars were apparent, hence, we should contradict them, i.e. we should not delay to that extent.”
Furthermore, we have queried the matter with the relevant experts, they too are of the opinion that the timetables are not accurate and there is a variation of at least two (2) minutes. Therefore, our advise is to exercise precaution by waiting at least five (5) minutes after the given time in our perpetual timetable.
And Allah Ta’ala Knows Best.
Mufti Ebrahim Desai
Answered by Shaykh Sohail Hanif, SunniPath Academy Teacher
We understand that the `Asr prayer, if offered before Maghrib time enters will be valid. And it will be valid even if only the opening takbeera was completed before the sun completed its setting and Maghrib entered. However the questioner (referring to a previous question) specifically says that the adhan had already sounded. I understand this to mean that the sun has already set completely. How could the `Asr prayer be valid and considered a current offering?
One’s offering of the Asr prayer, or indeed any other prayer, is legally valid as long as one utters the opening ‘Allahu Akbar’ before the end of that particular prayer time. If one starts a prayer after a prayer time has ended the prayer will count as a makeup and not a current offering and one will be guilty of having committed a major sin if done intentionally.
Both answers referred to in the question indicate that a person can still perform a current performance of Asr after the adhan of Maghrib. This seems to go against the aforementioned principle that a prayer must be commenced before the end of its prayer time; but in reality it does not.
Likewise when a prayer time commences according to a particular timetable, can one be certain that such a prayer time has actually started at the time stated? What if one’s watch is a few minutes too fast? What if the sun actually sets a minute after the time stated in the timetable? One can not be entirely certain. So in the very first minute of two of the entry of a prayer on a timetable one can reasonably say that one is uncertain that a particular prayer has started and so based on the above stated legal maxims one can pray a prayer from the previous prayer time. This is why it is generally recommended to not start praying a particular prayer or break one’s fast the very second the timetable states a prayer to have started but rather it is superior to wait a few minutes to ensure entry of that particular prayer time.
Some mosques allow for this slight error and delay their adhans slightly, like for example the Maghrib adhan in Amman which is generally about five minutes after the time stated in the timetable. Anybody starting their Asr prayer upon hearing this adhan has certainly missed the Asr prayer. Other mosques might start their adhan the very second stated in a timetable and it is with respect to such mosques that the previous two answers were given stating that one may pray the Asr prayer upon hearing the adhan of Maghrib and the prayer is still valid.
And Allah knows best.
Statements From Academics
DR VICTOR P. DEBATTISTA
Hi Dr. Debattista,
I spoke to you a couple of weeks ago on the phone. We do have a technical query and we were wondering if you can answer it for us.
We have looked at HMNAO sunset times and understand that they account for refraction in their calculations. However, we believe the calculations to be standard and static.
The Islamic tradition is to actually observe the sunset but normally Muslims take their times from the Observatory.
In classical application, a person would be observing the sunset and then opening their fast when the sun is no longer visible. Muslims need to use the sunset times to open their fasts during Ramadhan (after sunset) and to pray etc. In your opinion, is our recommendation of adding two minutes sufficient to the HMNAO times to account for the impact of refraction? This query is specifically for the times for Britain.
Our recommendation is purely as a precautionary measure to ensure that the sunset has occurred.
Does air pollution have any impact on HMNAO sunset times?
Can we publish your answer on our website with your answer?
We have asked this of a number of experts and will be looking at all of the replies comprehensively.
Thank you for your question.
The calculation that is being done by HMNAO, as per your link, requires that the Sun is half a degree below the horizon, which they determine means that the Sun is no longer visible even with refraction taken into account. The thing to keep in mind about refraction is that it is highly dependent on atmospheric conditions. Not so much pollution as turbulence (wind etc) and, especially, temperature variations in the atmosphere. These are basically weather patterns and, as usual, vary significantly by day and by location and are essentially impossible to predict with certainty. A search online showed that refraction as large as 2 degrees has been recorded historically!
It is worth pointing out that this was in Antarctica where one might expect temperature variations in the atmosphere to be more extreme.
So my conclusion as an astronomer is that allowing a further two minutes for the Sun to set is a good idea as a precaution but that one should always be aware that extreme (therefore unlikely but not impossible) conditions may result in the Sun reappearing when it should be well below the horizon. Another issue to be aware of is that sunset varies with altitude. At 12 km above the surface, as on a plane cruising, the horizon is 2 degrees lower, which means the Sun sets about 1.5 minutes later (in the UK). This probably affects a small number of people but it might be worth drawing your attention to it.
I hope this helps with your decision making. Please do let me know if you need more help with this and I will try my best to help you.
Yes, the correlation between sunset and latitude and the extreme scenario of the sun reappearing again is noted.
However we are making an assumption that the person is at ground level in the British isles and observing sunset on a typical day with no abnormal deviation.
Based on our assumptions, we would like to recommend adding extra two minutes to HMNAO times to British Muslims and I hope that in your opinion this will be sufficient?
And can we add your reponse with your name to our site?
Indeed, adding a further two minutes would ensure that any fluctuation due to turbulence, pollution or other factors is compensated for. You can add my name to the site.
(Dr) Victor P. Debattista
Professor of Astrophysics
Thank you for getting in touch — that is a very good question! Unfortunately, there is no simple answer.
First of all, it depends a little bit on exactly what you mean by “sunset”. The obvious definition is simply “when the sun has disappeared below the horizon”, but that will clearly depend on your surroundings — sunset will appear to be much early if you are in a valley surrounded by mountains, than if you are looking out to sea. In astronomy, we tend to choose a more consistent definition which is, in effect, “when the sun drops below the horizon that you would have if you could see the sea”. That still depends on your altitude (it will be a bit later if you are higher up) but it is more consistent and can be calculated accurately for any place on the surface of the Earth if the altitude is known.
However, there are some things that you cannot calculate in advance. The main one is refraction, as you say. When the sun seems to disappear below the horizon is actually later than when it really did drop low enough in the sky, as the light is bent by refraction through the air around the surface of the Earth and so you can still see the Sun a bit after it should have been blocked by the horizon (forgive me if I am telling you things you already know — I just want to make sure we are both talking about the same thing).
Unfortunately, the amount of refraction depends on a number of factors, some of which cannot be predicted. For example, the air pressure is important since that changes the “amount” of air between you and the horizon and hence the amount of refraction. Therefore, when calculating sunset time, we have to make an assumption. The simplest thing to do is assume there is no air (and hence no refraction) but that is very inaccurate, so we normally just assume a “standard” air pressure. That gives an answer which is correct on average, but will be a bit inaccurate on any given day.
To make things more complicated, as you move away from the equator, the angle that the Sun sets moves further away from the vertical (compared to the horizon) and changes during the year, so the amount of difference in sunset-time that a given amount of refraction makes varies from place to place and during the year.
For astronomers, we tend to deal with this by being pessimistic about sunset times. Since we are only really interested in knowing when the sky will definitely be dark, we tend to take the worst case, which around the UK usually means a maximum of about 6 or 5 minutes being added to sunset time from the “average refraction” calculations. However, such long delays are very rare — you are more likely to see no more than a couple of minutes extra delay, so your suggestion of adding 2 minutes would usually be fine.
Since this is not entirely predictable (even with quite a good weather forecast) you are probably going to have to decide what uncertainty you are comfortable with. If you want to be close to, but just after sunset most of the time, then adding 2 or 3 minutes to the HMNAO sunset times will be fine. If you want to be certain that sunset will be over, then you may want to add 5 or even 6 minutes.
I hope that helps — feel free to share this if you think it will be useful for others.
Prof Andy Newsam
Director of the National Schools’ Observatory
REFERENCES & ACKNOWLEDGEMENTS
- Air Pollution and Sunlight Q&A ↩
- What Is Refraction of Light? ↩
- Atmospheric Turbulence ↩
- Effect of atmospheric refraction on the times of sunrise and sunset ↩
- Refraction near the Horizon ↩
- A note on sunrise, sunset and twilight times and on the illumination conditions during twilight. ↩
- Why can we see the sun’s image before sunrise and after sunset? ↩
- Variability in the Astronomical Refraction of the Rising and Setting Sun ↩
- Variability in low altitude astronomical refraction as a function of altitude ↩