Posts Tagged ‘islamic astronomy’

UK Ramadan fasting times for 2017

May 22, 2017

Bismillah. As I’ve written about before, there are different views on excessive fasting hours in the summer at high latitudes such as the UK. I am not going to repeat those, but try to provide the scientific, astronomical data, information and knowledge to help support others to come to their own conclusions.

In this post, I give the dawn, sunset & possible fasting times for 2017, when mid-summer occurs towards the end of Ramadan: the average fasting times are slightly shorter than last year (2016), when they were maximum in the 33-year lunar/solar cycle, but not by much.

*I urge mosque timekeepers (muwaqqits) or others who develop fasting timetables to be transparent about the method they are using, and not vague references like “fiqh according to Madhhab X” because there are many views in every Madhhab. E.g. using an 18-degree or even 15-degree rule gives no timings for most of the UK. Fasting timetables in the UK summer should clearly state what method is used to arrive at the beginning time of fasting. Many timetables have excessive gaps between ‘dawn’ and sunrise of 2-3 hours with no sensible justification, since this is merely one possibility amongst many others and is indeed the most difficult for people. Indeed, with the summer midnight being at 1am BST, some of these timetables are forcing people to fast from soon after midnight. With the sunset-sunrise night length being 6-8 hours across the UK, the most reasonable view within this paradigm in my view is that of the last 1/6th, 1/7th or 1/8th of the night, giving a fasting time beginning an hour before dawn. However, other approaches are even more preferable. Over to others for discussion and to arrive at their own conclusions.*

Examples of dawn/sunset timings for the UK, 2017 (four UK capital cities)

This data is taken from HMNAO’s Websurf 2.0 website, and was reproduced with permission by the ASCL in their Ramadan 2017 guidelines. I have used the four UK capital cities, with three dates for each, roughly corresponding to the beginning, middle & end of Ramadan.

Date City Dawn (AST) Dawn (15D) Dawn (NAUT) Sunrise Sunset Fasting length (AST) Fasting length (15D) Fasting length (NAUT)
27 May London *** 0220 0305 0454 2103 *** 18:43 17:58
10 June   *** 0139 0245 0444 2117 *** 19:38 18:32
25 June   *** 0122 0243 0444 2122 *** 20:00 18:39
27 May Ed’burgh *** *** 0201 0441 2140 *** *** 19:39
10 June   *** *** *** 0428 2157 *** *** ***
25 June   *** *** *** 0428 2203 *** *** ***
27 May Cardiff *** 0232 0318 0506 2115 *** 18:43 17:57
10 June   *** 0152 0257 0456 2129 *** 19:36 18:32
25 June   *** 0136 0255 0457 2134 *** 19:58 18:39
27 May Belfast *** *** 0245 0500 2143 *** *** 18:58
10 June   *** *** 0159 0448 2158 *** *** 19:59
25 June   *** *** 0134 0448 2204 *** *** 20:30


AST
refers to astronomical twilight, when begins or ends when the sun is 18 degrees below the horizonKey:

15D refers to when the sun is 15 degrees below the horizon

NAUT refers to nautical twilight, when begins or ends when the sun is 12 degrees below the horizon

The astronomical definition of “dawn” is disputed, with various Muslim religious authorities adopting one of the three possible definitions given above.

*** in the above table means that the timing is not available, because the sun does not reach that far below the horizon. This happens every year during the summer at high latitudes, such as the UK.

 

NOTES:

  1. As confirmed by HMNAO, there is always a possible error of 1-2 minutes in sunrise and sunset timings: although we can calculate exactly the position of the sun relative to our horizons, refraction of the sun’s rays can introduce an error: the sun may be below the horizon but we see it just above, due to refraction.  (This does not always happen, of course: hence the error will be zero, one or two minutes.) This means that technically, mosque prayer timetables may wish to add 2 minutes to sunset timings and subtract 2 minutes from sunrise timings, just to be safe about the timings of the sunset and dawn prayers, and for breaking the fast.  However, this might also be hair-splitting: I recommend making these adjustments, but would not worry if they are not made.
  2. If we use astronomical twilight (Sun’s depression = 18 degrees) as the start of dawn, this does not occur at all during Ramadan 2017 in any of the four capital cities. Therefore, the fasting start time and fasting length would be undefined.
  3. If we use (Sun’s depression = 15 degrees) as the start of dawn, this does not occur at all during Ramadan 2017 in Edinburgh or Belfast. Therefore, the fasting start time and fasting length would be undefined in those cities. However, it does occur in London and Cardiff, giving fasting lengths of 19.5-20 hours during the month.
  4. If we use nautical twilight (Sun’s depression = 12 degrees) as the start of dawn, this results in fasting hours during Ramadan 2017 in London and Cardiff of 18-19 hours, and in Belfast of 19-20.5 hours. We only get defined fasting hours at the beginning of Ramadan for Edinburgh, of 19.5-20 hours.
  5. Hence, it should be obvious that some ijtihad is required, eg a fraction of the night or a lower angle of the Sun below the horizon to designate the “beginning” of dawn. Another option is sunrise-sunset fasting rather than dawn-sunset, as done by some of the Sahaba (Tafsir Ibn Kathir & Ibn Hazm’s Al-Muhalla), or other, non-literalist options that I have described elsewhere.

NB: Our local latitude determines the lowest angle the Sun will dip below the horizon at mid-summer (~22 June). This angle can easily be calculated by subtracting 66.5 degrees (the latitude of the Arctic & Antarctic Circles) from the local latitude.

E.g.:

Within the Arctic Circle (66.5 deg or higher latitude), lowest Sun angle = zero or higher: the sun doesn’t set at all in the “land of the midnight sun.”

Edinburgh (56.0 deg lat): lowest Sun angle at midsummer = 56.0 – 66.5 = 10.5 deg below the horizon

Belfast (54.6 deg lat): lowest Sun angle at midsummer = 54.6 – 66.5 = 11.9 deg below the horizon

London & Cardiff (both 51.5 deg lat): lowest Sun angle at midsummer = 51.5 – 66.5 = 15 deg below the horizon

*NB: even using these angles of 10.5 deg, ~12 deg, 15 deg & 15 deg for Edinburgh, Belfast, London & Cardiff respectively will give very long fasting hours, as the table of timings above demonstrates.

Btw for Paris (48.9 deg lat): lowest Sun angle at midsummer = 48.9 – 66.5 = 17.6 deg below the horizon, so using the 18-degree rule gives no timings for Paris or anywhere north of it either at midsummer.

Have a blessed Ramadan 1438 / 2017!

Usama Hasan, Fellow of the Royal Astronomical Society, UK

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UK Ramadan fasting times for last year (2016)

May 22, 2017

Bismillah. As I’ve written about before, there are different views on excessive fasting hours in the summer at high latitudes such as the UK. I am not going to repeat those, but try to provide the scientific, astronomical data, information and knowledge to help support others to come to their own conclusions.

In the first of these posts, I am including the dawn, sunset & possible fasting times from last year (2016) because then, mid-Ramadan coincided with mid-summer, hence giving the longest average fasting lengths in the 33-year cycle as the lunar years move through solar years.

Examples of dawn/sunset timings for the UK, 2016
(four UK capital cities)

This data is taken from HMNAO’s Websurf 2.0 website, and was reproduced with permission by the ASCL in their Ramadan 2016 guidelines. I have used the four UK capital cities, with three dates for each, roughly corresponding to: beginning, middle & end of Ramadan.

Date City Dawn (AST) Dawn (15D) Dawn (NAUT) Sunrise Sunset Fasting length (AST) Fasting length (15D) Fasting length (NAUT)
07 June London *** 0147 0248 0445 2114 *** 19:27 18:26
22 June (midsummer)   *** 0117 0241 0443 2122 *** 20:05 18:41
06 July   *** 0156 0256 0452 2118 *** 19:22 18:22
07 June Ed’burgh *** *** *** 0429 2154 *** *** ***
22 June (midsummer)   *** *** *** 0427 2203 *** *** ***
06 July   *** *** *** 0437 2158 *** *** ***
07 June Cardiff *** 0159 0300 0457 2126 *** 19:27 18:26
22 June (midsummer)   *** 0131 0254 0456 2134 *** 20:03 18:40
06 July   *** 0209 0308 0504 2130 *** 19:21 18:22
07 June Belfast *** *** 0209 0450 2156 *** *** 19:47
22 June (midsummer)   *** *** *** 0447 2204 *** *** ***
06 July   *** *** 0219 0457 2200 *** *** 19:41

Key:

AST refers to astronomical twilight, when begins or ends when the sun is 18 degrees below the horizon

15D refers to when the sun is 15 degrees below the horizon

NAUT refers to nautical twilight, when begins or ends when the sun is 12 degrees below the horizon

The astronomical definition of “dawn” is disputed, with various Muslim religious authorities adopting one of the three possible definitions given above.

*** in the above table means that the timing is not available, because the sun does not reach that far below the horizon. This happens every year during the summer at high latitudes, such as the UK.

 

NOTES:

  1. As confirmed by HMNAO, there is always a possible error of 1-2 minutes in sunrise and sunset timings: although we can calculate exactly the position of the sun relative to our horizons, refraction of the sun’s rays can introduce an error: the sun may be below the horizon but we see it just above, due to refraction.  (This does not always happen, of course: hence the error will be zero, one or two minutes.) This means that technically, mosque prayer timetables may wish to add 2 minutes to sunset timings and subtract 2 minutes from sunrise timings, just to be safe about the timings of the sunset and dawn prayers, and for breaking the fast.  However, this might also be hair-splitting: I recommend making these adjustments, but would not worry if they are not made.
  2. If we use astronomical twilight (Sun’s depression = 18 degrees) as the start of dawn, this did not occur at all during Ramadan 2016 in any of the four capital cities. Therefore, the fasting start time and fasting length were undefined.
  3. If we use (Sun’s depression = 15 degrees) as the start of dawn, this did not occur at all during Ramadan 2017 in Edinburgh or Belfast. Therefore, the fasting start time and fasting length were undefined in those cities. However, it did occur in London and Cardiff, giving fasting lengths of 19.5-20 hours during the month.
  4. If we use nautical twilight (Sun’s depression = 12 degrees) as the start of dawn, this resulted in fasting hours during Ramadan 2016 in London and Cardiff of ~18.5 hours, and in Belfast of just under 20 hours at the beginning and end of Ramadan, but not in mid-Ramadan (mid-summer). We had no defined fasting hours throughout Ramadan 2016 for Edinburgh.
  5. Hence, it should be obvious that some ijtihad is required, eg a fraction of the night or a lower angle of the Sun below the horizon to designate the “beginning” of dawn.

NB: Our local latitude determines the lowest angle the Sun will dip below the horizon at mid-summer (~22 June). This angle can easily be calculated by subtracting 66.5 degrees (the latitude of the Arctic & Antarctic Circles) from the local latitude.

E.g.:

Within the Arctic Circle (66.5 deg or higher latitude), lowest Sun angle = zero or higher: the sun doesn’t set at all in the “land of the midnight sun.”

Edinburgh (56.0 deg lat): lowest Sun angle at midsummer = 56.0 – 66.5 = 10.5 deg below the horizon

Belfast (54.6 deg lat): lowest Sun angle at midsummer = 54.6 – 66.5 = 11.9 deg below the horizon

London & Cardiff (both 51.5 deg lat): lowest Sun angle at midsummer = 51.5 – 66.5 = 15 deg below the horizon

*NB: even using these angles of 10.5 deg, ~12 deg, 15 deg & 15 deg for Edinburgh, Belfast, London & Cardiff respectively will give very long fasting hours, as the table of timings above demonstrates.

Btw for Paris (48.9 deg lat): lowest Sun angle at midsummer = 48.9 – 66.5 = 17.6 deg below the horizon, so using the 18-degree rule gave no timings for Paris or anywhere north of it either, at midsummer.

Usama Hasan, Fellow of the Royal Astronomical Society, UK

UK Ramadan dates, 2017-2025

May 22, 2017

Bismillah.

Ramadan dates 2017-2025 (approx.) for the UK

Based on Crescent Moon Visibility data for London from HMNAO’s Websurf 2.0 website

(Moon Visibility is now calculated very accurately on a scale of A-F. The following dates are based on the approximation that A-C represent a visible crescent moon; D-F represent an invisible moon.)

NB: The following dates may vary by 1 or 2 days because even with a visible crescent moon, there are intra-Muslim disagreements over how far this applies geographically.

YEAR Beginning of Ramadan Eid al-Fitr
2017 27 May 26 June
2018 17 May 16 June
2019 07 May 05 June
2020 25 April 25 May
2021 14 April 14 May
2022 03 April 02 May
2023 23 March (~ Spring equinox) 22 April
2024 12 March 10 April
2025 02 March 31 March

 

A beginner’s guide to learning about astronomy

October 9, 2009

Bismillah. Some recommendations:

1) All knowledge comes from God, so continually pray to him to teach you more. This Koranic prayer is great: rabbi zidni ‘ilma(n) – “My Lord, increase me in knowledge.”

2) The first and last learning resource for astronomy is the sky itself, especially the night sky. Get into the habit of watching the movement of the sun and moon, where and when they rise and set etc. (Never look directly at the sun.) Sunrise/sunset and moonrise/moonset times are widely-available online and in good daily newspapers.

The apparent movement of stars and planets would be the next thing to learn. Make sure you know your N-E-S-W directions wherever you are. Learning about the North Star helps here! Binoculars are good for viewing the moon and fainter stars.

3) Visit the Royal Observatory Greenwich (ROG), http://www.rog.nmm.ac.uk – free entry with brilliant learning resources, planetarium shows and a good shop for books, software and telescopes.

4) There are many observatories and planetaria around the UK – do try to visit those.

5) Watch “The Sky at Night” on BBC1, it’s a monthly programme. Has a good website, too.

6) There are several national and international astronomical associations and astronomy magazines. The latter include “Astronomy Now” and “Sky and Telescope.” There are hundreds of websites.

7) Software: free, shareware or fairly cheap, and will show you on your PC screen what the night sky looks like at your location, at any time. “Starry Night” is about £10 at the ROG shop, and is excellent. Skyglobe is good shareware, available online. Others include Stellarium, but I’m not familiar with them. A good way to learn to recognise and name the planets, stars and constellations.

8. Many observatories, including ROG, run short courses with weekly sessions, teaching astronomy at beginner and more advanced levels, as do many adult-learning colleges. For children, there are GCSE and AS-level courses in astronomy.

9) My blog (https://unity1.wordpress.com) has a section on astronomy and Islamic astronomy.

10) There are many books on Islamic astronomy. Good websites include ICOP, the Astronomical Societies of Jordan, the UAE and Qatif in Saudi Arabia (qasweb.org) and various moonsighting ones.

TV programme – Moonsighting discussion

August 16, 2009

Bismillah. We just finished recording this, alhamdulillah.

It will be aired on Islam Channel (Sky 836 or http://www.islamchannel.tv) on Tuesday night God-willing, 18th August 2009, 10-11pm.

Panellists (with a studio audience):

Mohammad Ali (Islam Channel)
Qamar Uddin (ICOP)
Suliman Gani (Tooting Mosque)
Usama Hasan (Tawhid Mosque)

Chair: Ajmal Masroor

A good discussion I thought, more civilised and less heated than in previous years. I hope it will be beneficial in advancing public understanding of the issues involved.

Ibn Taymiyyah on Fasting and Moonsighting

July 14, 2009

Ibn Taymiyyah – Fasting and Moonsighting v1 (16 pages including commentary by Usama Hasan)

From the Collected Fatwas of Ibn Taymiyyah (Majmu’ Fatawa Shaykh al-Islam Ibn Taymiyyah), ed. ‘Abd al-Rahman b. Qasim and his son Muhammad, Riyadh, 1398 H, vol. 25 (vol. 5 of the Fiqh Section), pp. 98-113.

TABLE OF CONTENTS

1 Fasting on the day when it might or might not be the first of Ramadan
1.1 Caution in legal matters
1.2 Does the hilal exist only when it is visible, or does it have an independent existence?

2 How far geographically is a hilal-sighting valid?

2.1 The impact of knowledge and communication constraints on this matter
2.2 Travelling to a place where Ramadan began on a different day
2.3 The importance of information in this matter
2.4 The meaning of “hilal”
2.5 Summary of the discussion so far
2.6 A further discussion about the hilal and the Hajj

An Introduction to the Moonsighting Controversy

July 14, 2009

Introduction to Moonsighting Controversy

A good 10-page summary of the main issues, by Rukhsana Begum.