Presentation on theme: "An Introduction to Islamic Astronomy (al-Falak al-Shari) Usama Hasan Islamic Circles, Muslim World League, Saturday 25 th Shaban 1428 / 8 th September."— Presentation transcript:
An Introduction to Islamic Astronomy (al-Falak al-Shari) Usama Hasan Islamic Circles, Muslim World League, Saturday 25 th Shaban 1428 / 8 th September 2007 With the Name of Allah, All-Merciful, Most Merciful
Who will benefit, in sha Allah Students of Islamic law (Shariah) Students of mathematics, physics, astronomy, etc. Mosque imams Mosque time-keepers (muwaqqits) Others …
Synopsis 1. Geometry and Motion of the Earth 2. Qiblah 3. Prayer Times 4. Moonsighting
1 – The Geometry of the Earth Latitude Longitude North Pole South Pole The Seasons
Motion of the Earth The Earth spins on its axis once in 24 hours (from west to east): one day and night The axis of the Earths spin is inclined at 23.5 deg to the direction of its motion around the Sun
1a - Latitude The Equator The Tropic of Cancer (23.5 deg N) The Tropic of Capricorn (23.5 deg S) Local latitude is given by the altitude of the North Star (northern hemisphere only)
1b - Longitude The Greenwich Meridien Lines of longitude as time zones 360 deg / 24 = 15 deg The International [Solar] Date Line (ISDL or IDL): 180 deg E / W
1c – The Poles At the North Pole, all directions are South At the South Pole, all directions are North The North Star (Pole Star, Polaris, al-najm al-shimali, najm al-qutb) is directly above the North Pole The Earths axis points to the North Star
1d – The Seasons: Earths Annual Motion around the Sun
The Seasons (contd) At the Spring & Autumn equinoxes, the Sun is directly above the Equator At the Winter Solstice, the Sun is directly above the Tropic of Capricorn At the Summer Solstice, the Sun is directly above the Tropic of Cancer (For northern hemisphere: vice-versa for the southern hemisphere)
The Seasons – Implications for Shadow Lengths Between the Tropics (i.e. in Tropical and Equatorial regions of the earth), there are times during the year when the Sun is directly overhead at noon Shadows sometimes disappear at noon Outside the Tropics (north and south), the Sun is never directly overhead at noon Shadows never disappear at noon
Annual Motion of the Sun, Moon, Planets & Stars Lord of the Two Easts, Lord of the Two Wests! So which of the favours of your Lord will you deny? (al-Rahman 55:17-18) Lord of the East(s) and West(s) … (Muzzammil 73:9, Maarij 70:40)
Annual Motion of the Sun, Moon, Planets & Stars (Q. 55:17) S E W N N SUMMER SOLSTICE WINTER SOLSTICE EQUINOXES Easts (Multiple, Two limits) Wests (Multiple, Two limits)
Sunrise and Sunset SeasonSunrise direction Sunset direction AutumnEastWest WinterSESW SpringEastWest SummerNENW
2- Qiblah formulae !!! For Istanbul:
Qiblah Direction: Great Circles A Great Circle is a circumference of the Earth that has the centre of the Earth at its centre All lines of longitude are Great Circles No line of latitude is a Great Circle, except for the Equator, which is a GC There are many inclined Great Circles
Examples of Great Circles
Comparison of Great Circle Route and Loxodrome on the Mercator Projection. The loxodrome is a line of constant heading, and the great circle, although appearing longer than the loxodrome, is actually the shortest route between New York and London.
Qiblah direction The correct qiblah direction is always a Great Circle direction … unless you believe that the Earth is flat E.g. from the USA, is the qiblah SE or NE ?
Tips for finding the qiblah - 1 Use The Plough and Polaris to determine North In Somalia, Polaris tells us the qiblah!
Tips for finding the qiblah - 2 Use the direction of sunrise and sunset during the seasons
Tips for finding the qiblah - 3 At noon (zawal), the Sun is always: Due South if you are north of the Tropic of Cancer Due North if you are south of the Tropic of Capricorn Between the Tropics, it will be overhead, N or S
Tips for finding the qiblah – 4 (Khalid Shaukat): When the Sun is overhead at the Kabah: It is not advisable to determine the Qibla specially for a Masjid using an ordinary compass. The following method which uses the sun is more reliable and accurate. It has been observed for centuries and reported in many books by Muslims around the world that two times a year the sun comes overhead above Ka'bah. This is observational fact for centuries, and is used to set the correct Qibla direction in places far from Makkah by Muslims for last so many centuries. Those two dates and times are: May 28 at 12:18pm Local Civil Time at Makkah July 16 at 12:27pm Local Civil Time at Makkah
Tips for finding the qiblah – 4a Local Time facing sun gives Qibla PLACEMay 28 July 16 Afghanistan13:48 13:57 Bangladesh15:18 15:27 Bosnia11:18*11:27* Burma15:1815:27 Canada, Montreal15:18*5:27* Egypt11:1811:27 France11:18*11:27* Germany11:18*11:27* India14:4814:57 Indonesia,Jakarta16:1816:27 Iran13:48*13:57* Malaysia17:18 17:27 Pakistan14:18 14:27 Palestine12:18*12:27* South Africa11:1811:27 United Kingdom10:18*10:27* * means that these times are local Daylight Saving Times as observed in those countries. This method applies at local Makkah noon between and around these two dates also, because Makkah is only two degrees from the Tropic of Cancer, i.e. the method applies throughout May, June and July with good accuracy (UH)
Tips for finding the qiblah - 5 Use a compass or qiblah compass Magnetic north is near true north Effect of metal / steel structures, e.g. inside modern office/apartment blocks
Tips for finding the qiblah - 6 If all else fails … Most satellite dishes in UK point SE ! Hadith, What is between the East and the West is the qiblah, based on the ayah, To Allah belongs the East and the West: wherever you turn, there is the Face of God.
Daily Prayer Times (Solar) Establish the Prayer from the Decline of the Sun until the Darkness of the Night, and the Dawn Recitation … (Quran, 17:78)
Fajr (Dawn) False dawn, like foxs tail True dawn Angle of Sun beneath horizon: deg? 90-minute rule for the UK Impossible to calculate precisely?
Zuhr (Afternoon) Immediately after Zawal (Noon) Half-way between sunrise and sunset
Asr (late afternoon) When sun is lower, cooler, yellower One- or two- shadows length? Easiest way to determine: half-way between noon and sunset
Maghrib (Sunset) When the whole of the suns disc disappears below the horizon Calculations of sunset (and sunrise) have an error of 1-2 minutes either way because of refraction Important for prayer and iftar !
Isha (Night) When the red or white twilight disappears When it gets dark & the stars come out Angle of Sun beneath horizon: deg? 90-minute rule for the UK Impossible to calculate precisely?
Tips on Prayer Times Try not to use a watch or prayer timetable! But if you must … Problem of Fajr / Isha time in the Summer …
4 - Moonsighting
The Moon - Basic Facts The Earth travels around the Sun once every 365 days (and 6 hours) The Moon travels around the Earth once every 29 ½ days A lunar year of 12 lunar months has 355 days Phases of the moon result from parts of the Moon reflecting the Suns light towards the Earth A lunar month has either 29 or 30 days (hadith)
Phases of the Moon
Looking for the New Crescent Only visible after sunset Must wait for the suns glare to die down Experience shows that the best time to see the crescent is about 20 minutes after sunset (when the sun is 5° below horizon) Perfect timing if the Sunnah is followed (Salat al-Maghrib should be fairly short) Look at the western horizon, near where the sun set
The MOONWATCH Project Launched 1 st Oct 2005 & will run for several years (www.crescentmoonwatch.org)www.crescentmoonwatch.org A mass-experiment for the UK public Part of Einstein Year (2005 is 100 years since the publication of Relativity theory) Everyone is encouraged to look for the new crescent every month and report their observations via the above website Will help improve HM Nautical Almanac Offices crescent-visibility calculations, in sha Allah
Moonsighting - History The Islamic calendar is a purely lunar one Islam abolished the Pre-Islamic Arabian method of intercalation Until relatively recently, the start of each lunar month was determined purely by observation of the new crescent moon If cloudy, use a simple alternating 29/30 day rule Communication constraints meant there was no controversy across the vast Muslim lands
Moonsighting – Islamic Law (1) The Shariah (Sacred Law) covers all areas of life Basic rule: crescent-sighting establishes the new month Calculations: controversial; different views Cannot be used to determine new month Can be used to reject false crescent-sightings Can be used to determine new month
Moonsighting – Islamic Law (2) Applicability of a valid crescent- sighting: two views that can be unified One view: ikhtilaf al-matali (multiple horizons) Crescent-sighting applies only locally Nowadays: each state has its own horizon Another view: ittihad al-matali (unified horizons) A single sighting applies for the whole (Muslim) world
Background - Calculations Accurate calculations for the position of the moon have been around for thousands of years E.g. solar and lunar eclipses However, calculation of the visibility of the new crescent moon has only become significantly accurate over the last ~20 years Yallop, Ilyas, etc. Usually, the moon needs to be hours old before the crescent is visible Using conjunction (astronomical birth) means the month will start one day too early
Calculating Crescent Visibility Simple prediction rules have existed for millenia (ancient Babylon, Greece, classical Islam, e.g. al-Bayruni, etc.) Modern criteria have been developed by: Bernard Yallop (ex-director of the Royal Observatory Greenwich) Mohammad Ilyas (Malaysia) Schaefer (kept the details secret) Odeh (Jordanian Astronomical Society)
Calculating Crescent Visibility (2) Moonsighting.com is based on Yallop/Ilyas and uses five factors only: 1. The angle between Sun and Moon 2. The (angular) height of the Moon above the horizon 3. Earth-Moon distance 4. Earth-Sun distance 5. A measure of pollution in the atmosphere Moonsighting.coms predictions have proved accurate every month since 1994!
Towards a Unified Lunar Calendar With accurate calculations of crescent- visibility, a worldwide lunar calendar is now possible (Ahmad Shakir, Qaradawi, Kamali, etc.) There are 3 major possibilities: 1. Use the visibility curve as an ILDL 2. Fix everything wrt one place, e.g. Mecca 3. Compromise: the Unified Hejra Calendar (divide the world into three time zones)
Proposal 1: Crescent-Visibility curve as ILDL (International Lunar Date-Line) 1 Dhul Qadah Shawwal 1426
Proposal 2: Fix everything wrt one place, e.g. Makkah Makkah 1 Dhul Qadah Shawwal 1426
Proposal 3: the Unified Hejra Calendar (www.icoproject.org) Central Region Western RegionEastern Region
Proposal 3: the Unified Hejra Calendar (www.icoproject.org) Central Region Western RegionEastern Region For Dhul Qadah 1426, ILDL coincides with the Solar dateline