BUKU FALAK ABAD 21

Jabatan Ukur dan Pemetaan Malaysia (JUPEM) dan Jabatan Kemajuan Islam
Malaysia (JAKIM) dengan menggunakan teodolit bermula tahun 1972.
Kemudian, pada tahun 1979 pula, penggunaan teleskop Questar Seven berjejari 7
inci diperkenalkan bagi tujuan cerapan anak bulan sebagaimana ia berfungsi
menghasilkan tahap-tahap pembesaran mengikut kehendak pengguna yang
bersesuaian dengan tempat dan ketika untuk memerhatikan anak bulan.
Perkembangan peralatan astronomi di dunia memberi impak yang sesuai kepada
perkembangan peralatan astronomi di Malaysia khususnya dalam cerapan anak
bulan. Kini, cerapan anak bulan turut dilakukan dengan bantuan alatan astronomi
seperti teleskop utama, teleskop sekunder, kamera Digital Single Lens Reflex
(DSLR), hygrometer, perisian astronomi, dan alat pengukur cahaya (digital light
meter). (Abdul Niri et al., 2012) Namun begitu, kadangkala timbul permasalahan
daripada aspek pengisbatan anak bulan menurut hukum fiqh apabila anak bulan
tidak kelihatan secara fizikal namun imejnya berjaya dirakam pada kamera DSLR
yang dipancarkan kepada skrin komputer riba menerusi teknik pengimejan ketika
cerapan anak bulan dilakukan. (Nurul Kausar Nizam et al., 2014) Isu seperti ini
turut dibincangkan oleh para ulama’ dan cendekiawan falak/astronomi islam bagi
mencari titik temu yang boleh menghubungkan antara teknik moden dalam
mencerap anak bulan dan hukum fiqh yang disabitkan ke atasnya.

Pada 9 Ogos 2021 yang lalu, bersempena Sambutan Bulan Falak Malaysia
Tahun 2021, Ketua Pengarah Jabatan Kemajuan Islam Malaysia (JAKIM), Datuk
Abdul Aziz bin Jusoh telah mengadakan Pelancaran Penggunaan Kriteria Imkan
al-Rukyah (KIR) Baharu MABIMS (dalam penyediaan Takwim Hijrah bermula
Muharam 1443H). Keputusan itu adalah berdasarkan persetujuan oleh negara-
negara anggota MABIMS (Malaysia, Brunei, Indonesia dan Singapura) dalam
Mesyuarat Pegawai-Pegawai Kanan Negara MABIMS di Singapura pada tahun
lalu. (Subkhi Sudarji, 2021) Ini menunjukkan bahawa ilmu sains kenampakan
anak bulan sentiasa berkembang mengikut peredaran zaman.

PENDEKATAN AL-SUBKI DALAM PENENTUAN ANAK BULAN

Taqi al-Din al-Subki di dalam kitabnya telah menyebutkan bahawa hisab boleh
berperanan menentukan kesaksian kenampakan anak bulan seseorang
sebagaimana firman Allah s.w.t:

(‫)يَ ْسأَلُونَ َك َع ِن اْلَِهَلِّة ۖ قُ ْل ِه َي َمَواقِي ُت لِلَنّا ِس َواْْلَ ِج‬
Terjemahan: “Mereka bertanya kepadamu tentang bulan sabit. Katakanlah: “Bulan sabit
itu adalah tanda-tanda waktu bagi manusia dan (bagi ibadah haji)”.

(Surah al-Baqarah, 2: 189)

Menurut beliau, anak bulan amat berkait rapat dengan hukum-hukum
fiqh sebagai penanda waktu bagi pelbagai urusan manusia. Hal ini merangkumi
waktu solat hari raya, zakat, berpuasa Ramadan, hari Aidilfitri, umur kambing,
unta dan lembu yang perlu dibayar zakat, beri’tikaf bagi yang bernazar, haji,

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wuquf, korban, aqiqah, sembelihan, jual beli, umur baligh, sumpah (ila’), kaffarah
bersetubuh di siang hari (berpuasa), zihar, hukuman pembunuh dengan berpuasa,
iddah disebabkan kematian, bagi wanita yang putus haid, kosongkan rahim
(istibra’), penyusuan, menasabkan anak kepada seseorang, pakaian isteri, diat dan
urusan lain-lain yang memerlukan untuk mengetahui waktu atau tempoh waktu
untuk yang berkaitan dengan kalendar Hijrah. (Al-Subki, t.t.)

Al-Subki menjelaskan bahawa penentuan awal bulan yang berdasarkan
peristiwa ijtimak adalah tidak diterima sebagaimana ia tidak bertepatan dengan
syarak kerana menyalahi isyarat Nabi s.a.w yang bersabda bahawa masyarakat
arab pada zaman dahulu merupakan golongan yang ummi iaitu tidak tahu menulis
mahupun mengira. Berdasarkan kenyataan al-Subki, faktor lain yang
mempengaruhi kenampakan anak bulan adalah pencemaran udara dan
kejernihannya, pembentukan anak bulan dari arah utara atau selatan, perbezaan
kedudukan bulan terbit dan terbenam serta perbezaan kedudukan bintang terbit
dan terbenam perlu diperhatikan dalam situasi ini. Pendapat al-Subki boleh
dijadikan panduan untuk mengambil kira teknik-teknik tertentu dalam
pengisbatan anak bulan. Menurutnya lagi, penentuan waktu solat memadai
dengan pengiraan hisab falak untuk menentukan awal dan akhir waktu solat.
Namun begitu, dalam konteks anak bulan penentuannya bukan disebabkan oleh
kewujudan bulan tersebut di ufuk barat, tetapi kewujudannya mesti boleh dikesan
dan berkemungkinan untuk dilihat. Hal ini bertepatan dengan sabda Nabi s.a.w
iaitu: “Berpuasalah kamu apabila melihat anak bulan dan berbukalah (berhari
raya) sekiranya melihat anak bulan”. Oleh itu, jelas ditekankan bahawa syarak
menjadikan kenampakan hilal sebagai sebab untuk berpuasa dan al-Subki turut
menegaskan adalah tidak memadai untuk memulakan awal bulan yang baharu
dengan hanya berpandukan ijtimak. (Al-Subki, t.t.)

Peredaran fasa bulan dan pergerakan matahari merupakan perkara utama
yang perlu difahami dalam hal penentuan awal bulan Hijrah ini. Menurut al-Subki,
elemen yang terlibat dalam konsep imkan al-rukyah adalah ketinggian anak bulan
dari ufuk (qaus al-rukyah) yang juga dikenali sebagai altitud iaitu jarak sudut
antara ufuk dan anak bulan (Odeh, 2004). Selain itu melibatkan aspek sudut
elongasi (qaus al-nur) yang bermaksud jarak sudut antara matahari dan anak bulan
(Odeh, 2004). Seterusnya, beliau juga menyebutkan tentang sela masa antara
bulan terbenam dan matahari terbenam (qaus al-makh) yang juga dikenali sebagai
lag time (Odeh, 2004) dalam ilmu sains kenampakan anak bulan. Ketiga-tiga
elemen ini dapat dilihat menerusi Rajah 1. Al-Subki turut menyatakan, terdapat
ahli astronomi yang berpendapat anak bulan kelihatan tidak kelihatan sekiranya
nilai qaus al-rukyah sebanyak 6° manakala qaus al-nur pula 9° dan qaus al-makh
bersudut 9°. Namun begitu, anak bulan berkemungkinan kelihatan sekiranya
nilai-nilai darjah tersebut bertambah.

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Terdapat juga situasi hisab menunjukkan keadaan anak bulan itu masih tidak
imkan al-ru’yah, seperti kedudukan anak bulan tersebut dekat dengan matahari,
maka mustahil untuk melihatnya dengan pancaindera. Sekiranya terdapat
perkhabaran daripada seseorang atau lebih yang melihat anak bulan tersebut,
maka perkhabaran tersebut dianggap bohong atau terdapat kesalahan. Bahkan
sekiranya walaupun terdapat seorang saksi ataupun dua orang saksi yang melihat
anak bulan, maka penyaksian mereka juga tidak boleh diterima. Ini kerana, hisab
itu bersifat qat’i, sedangkan syahadah dan khabar itu kedua-duanya adalah zhanni.
Maka, sesuatu yang zhanni tidak boleh menandingi yang qat’i. Syarat dalam
bayyinah adalah apa yang disaksikan itu mungkin (diterima) dari segi akal dan juga
syarak. Jika sekiranya hisab secara pasti menunjukkan tidak imkan, maka mustahil
diterima dari segi syarak akan kenampakan anak bulan tersebut. Syarak tidak
akan menerima sesuatu perkara yang mustahil. Maka setiap yang telah kita lihat
dan kita dengar, wajib ke atas hakim untuk menyelidiki pengakuan itu sama ada
betul atau sebaliknya. Ini dapat diperolehi daripada keilmuan hakim, ataupun
dengan merujuk kepada mereka yang thiqah dalam ilmu ini. Sekiranya hisab
mengatakan bahawa tidak mungkin rukyah (‘adam al-ru’yah) maka tidak perlu
diterima kesaksian. Maka perlu kekalkan bulan yang berlangsung dengan
mencukupkan bilangan harinya kepada 30. Ini menunjukkan bahawa syarak tidak
mengabaikan pendapat ahli hisab secara mutlak. (Al-Subki, t.t.)

RELEVANSI PEMIKIRAN AL-SUBKI DALAM PENENTUAN ANAK
BULAN PADA ERA REVOLUSI INDUSTRI 4.0 DI MALAYSIA

Penentuan kenampakan anak bulan selepas berlaku penjajaran atau ijtimak antara
bulan, matahari dan bumi adalah agak sukar kerana melibatkan beberapa faktor
seperti kedudukan bulan dan matahari relatif pada ufuk tempatan, relatif
kecerahan anak bulan berbanding kecerahan langit, dan faktor kecerahan
atmosfera. Ini merupakan satu cabaran menurut ahli astronomi untuk melihat
bulan yang paling kecil kerana selain daripada aspek astronomi, ia turut
mengambil kira aspek meteorologi dan psikologi pencerap. (Mohd Nawawi et al.,
2020) Pada arus permodenan dan kecanggihan teknologi masa kini membolehkan
pencerap merekodkan kenampakan anak bulan di bawah kriteria kenampakan
anak bulan. Contohnya, pada 15 Mei 2008, Martin Elsässer iaitu ahli astronomi
Jerman telah berjaya merekodkan gambar anak bulan sebelum matahari
terbenam, di mana anak bulan tersebut direkodkan beberapa minit selepas
berlakunya ijtimak. Malah sebelum itu juga, pada Jun 2007 dengan bantuan
pemprosesan imej (image processing), beliau dapat melihat anak bulan pada
waktu siang hari jauh di bawah kriteria kenampakan anak bulan. Pada 14 April
2010 dan 8 Julai 2013 dengan menggunakan teknik tertentu, seorang ahli
fotogarafi di Perancis mampu merekodkan gambar kenampakan anak bulan pada
waktu tengah hari selepas berlakunya ijtimak. Disamping itu, dengan
perkembangan sains dan teknologi banyak perisian dan teknik pemprosesan imej
diperkenalkan oleh ahli astronomi dalam mengesan kemunculan anak bulan

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seperti Circular Hough Transform (CHT) dan anak bulan berjaya dikesan dengan
lebih awal menggunakan teknik radio astronomi. (Umar et al., 2017) Terdapat
pendapat di kalangan ulama menunjukkan bahawa harus berpegang kepada wujud
anak bulan dan imkan al-ru’yah, sama seperti penentuan waktu solat yang
menggunakan hisab perkiraan walaupun pada hari yang terdapat halangan seperti
awan, jerebu dan sebagainya. Hal ini demikian kerana, dalam penentuan waktu
solat memadai hanya dengan pengiraan hisab falak untuk menentukan awal dan
akhir waktu solat. Namun, al-Subki menyatakan bahawa, beliau menolak
permulaan bulan baharu yang dimulakan apabila berlakunya ijtimak, iqtiran atau
conjunction kerana dalam konteks anak bulan, penentuannya bukan disebabkan
oleh kewujudan bulan tersebut di ufuk barat, tetapi kewujudannya mesti boleh
dikesan dan berkemungkinan untuk dilihat. Maka, permulaan bulan yang baharu
perlu berpandukan kepada rukyah atau lebih tepat lagi adalah berpandukan
kepada imkan al-rukyah.

Perkembangan peralatan astronomi di Malaysia khususnya dalam cerapan
anak bulan turut berkembang pada era Revolusi Industri 4.0. Kini, cerapan anak
bulan dilakukan dengan bantuan alatan astronomi seperti teleskop utama,
teleskop sekunder, kamera Digital Single Lens Reflex (DSLR) serta komputer
riba. Namun, ada kalanya timbul permasalahan daripada aspek pengisbatan anak
bulan menurut hukum fiqh apabila anak bulan tidak kelihatan secara fizikal
namun imejnya berjaya dirakam pada kamera DSLR yang dipancarkan kepada
skrin komputer riba menerusi teknik pengimejan ketika cerapan anak bulan
dilakukan. Dalam hal ini, kaedah hisab yang lebih bersifat qat’i dapat membantu
kesahan kesaksian kenampakan anak bulan melalui kaedah rukyah. Meskipun
anak bulan tersebut tidak kelihatan ketika cerapan dilakukan walaupun telah
memenuhi kriteria imkan al-rukyah, maka keesokan harinya tetap akan dikira
sebagai bulan baru kerana imkan al-rukyah menjadi penentu dalam penetapan
awal bulan di Malaysia. Pendapat ini bertepatan dengan pandangan al-Subki yang
menyatakan bahawa hisab itu bersifat qat’i, sedangkan syahadah dan khabar itu
kedua-duanya adalah zhanni. Maka, sesuatu yang zhanni tidak boleh menandingi
yang qat’i. Syarat dalam bayyinah adalah apa yang disaksikan itu mungkin
(diterima) dari segi akal dan juga syarak. Jika sekiranya hisab secara pasti
menunjukkan tidak imkan, maka mustahil diterima dari segi syarak akan
kenampakan anak bulan tersebut. Maka, bagi permasalahan imej anak bulan
berjaya dirakam pada kamera DSLR sedangkan secara fizikal anak bulan tidak
kelihatan, diterima kenampakan tersebut kerana menurut hitungan astronomi
(hisab) anak bulan itu telah memenuhi kriteria imkan al-rukyah.

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RUMUSAN

Kesimpulannya, pendekatan al-Subki dalam menentukan anak bulan adalah
bertepatan dengan hisab yang melibatkan pengiraan dan formula matematik
terperinci dan kompleks yang selari dengan arus permodenan semasa dalam
kategori hitungan astronomi. Selain itu, al-Subki turut menerima teknik
pemprosesan imej dan penggunaan pelbagai peralatan astronomi moden dalam
aktiviti cerapan anak bulan di mana keduanya telah digunakan secara meluas pada
zaman ini dengan kehadiran teknologi yang lebih canggih selagimana menepati
syarat imkan al-rukyah. Berdasarkan perkara tersebut, pendekatan Taqi al-Din al-
Subki dalam penentuan anak bulan adalah relevan pada era Revolusi Industri 4.0.

PENGHARGAAN

Kertas kerja ini telah dibiayai oleh geran penyelidikan IIRG002D-19FNW
Penentuan Awal Bulan Hijrah: Analisis Perbandingan Di Asia Tenggara.

RUJUKAN

_______________________
a Islamic Astronomy Programme, Academy of Islamic Studies University of
Malaya, 50603, Wilayah Persekutuan Kuala Lumpur, Malaysia
* Nurul Syakirah binti Rahiman: [email protected]
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Ahmad Zaki, N. (2012). Kesan Penggunaan Hitungan Astronomi Dan Alatan
Moden Dalam Cerapan Hilal Di Malaysia : Satu Penelitian. Jurnal Fiqh, 9(9), 45–
64.
[2] Abu, Samad. (2001). Kaedah Penentuan Awal Hijrah. Jabatan Kemajuan Islam
Malaysia.
[3] Al-Subki, Taqi al-Din ‘Ali bin ‘Abd al-Kafi. (t.t). Adillah fi Ithbat al-Ahillah.
[4] Al-Subki, Taqi al-Din ‘Ali bin ‘Abd al-Kafi. (t.t). al-Fatawa al-Subki (1st ed.).
Dar al-Ma’arif.
[5] Ilyas, M. (1994). Lunar crescent visibility criterion and Islamic calendar.
Quarterly Journal of the Royal Astronomical Society, 35, 425.
[6] Mohd Nawawi, M. S. A., Wahid, K., Man, S., Ahmad, N., & Abdul Niri, M.
(2020). Pemikiran Imam Taqī Al-Dīn Al-Subkī ( 683 / 1284-756 / 1355 )
Berkaitan Kriteria Kenampakan Anak Bulan. Jurnal Syariah, 28(1), 1–30.
[7] Mohd Saiful Anwar, M., Saadan, M., Mohd Zambri, Z., Raihana, A., &
Nurulhuda, A. (2015). Sejarah Kriteria Kenampakan Anak Bulan di Malaysia.
Jurnal Al-Tamaddun, 10(2), 62.
[8] Muhammad, N. B. (2017). Al-Shaykh Taqi al-Din al-Subki: Dirasah ‘An
Duwarih fi al-Hayah al-Fikriyyah wa al-Qada’iyyah. Humanities Journal of
University of Zakho, 5(3), 676–685.

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[9] Nurul Kausar Nizam, Mohd Saiful Anwar Mohd Nawawi, Mohammaddin
Abdul Niri, Saadan Man, & Mohd Zambri Zainuddin. (2014). Penggunaan
Teleskop: Kesan Terhadap Hukum Ithbat Kenampakan Anak Bulan di Malaysia.
Jurnal Fiqh, 11(11), 55–74.
[10] Odeh, M. S. (2004). New criterion for lunar crescent visibility. Experimental
Astronomy, 18(1–3), 39–64. https://doi.org/10.1007/s10686-005-9002-5
[11] Subkhi Sudarji. (2021). Jakim anjur program Bulan Falak Malaysia Tahun
2021. Utusan Malaysia. https://www.utusan.com.my/terkini/2021/08/jakim-
anjur-program-bulan-falak-malaysia-tahun-2021/
[12] Umar, R., Kamarudin, M. K. A., Khairuldin, W. M. K. F. W., Nawawi, M. S.
A. M., & Jusoh, dan A. J. M. (2017). Observations of the New Moon using
Optical Telescopes and Radio Telescope from the Perspective of Islam.
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561–574. https://doi.org/10.6007/ijarbss/v7-i8/3262
[13] Wan Muda, W. M. (1993). Kaedah Sains dan Pelaksanaan Penyelidikan:
Suatu Penilaian Bersepadu. In M. Y. O. et Al. (Ed.), Siri wacana Sejarah dan
Falsafah Sains (p. 47). Dewan Bahasa dan Pustaka.
[14] Zainuddin, M. Z., Mohd Saiful Anwar, M. N., & Ahmad, N. (2010). Sky
Illumination For Lunar Crescent’s Visibility in Teluk Kemang Malaysia. 5–51.

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A STUDY ON IMPACT OF COVID-19 ON LEVEL OF LIGHT
POLLUTION AND ASTRONOMICAL SIGHTING IN
MALAYSIA

Muhamad Syazwan Faida, Mohd Saiful Anwar Mohd Nawawia*, Mohd
Paidi Normanb

Abstract: The rampage spread of COVID-19 causes a immediate
lockdown on populated cities in Malaysia. As lockdown limits the
economic activity, it will reduce the level of light pollution as nighttime
activity is restricted. This will provide an ample opportunity to study the
level of light pollution on natural night sky without the obstruction of
artificial lighting. The impact of the reduced level of light pollution can
also studied on astronomical visibility, animal activity and long-term
human health. This study will use the Satellite data of VIIRS from
lightpollution.info to assess the level of light pollution, and data of
moon sighting in International Crescent Observation Project, during
pre and post COVID-19. These data are selected as its represent the
impacts of light pollution, which are astronomical visibility, and human
activity. The study found impacts of COVID-19 lockdown to level of
light pollution and astronomical sighting. There are 0.2 mag/sec2 for
urban location, and 4 precent increase of successful moon sighting. The
paper demonstrate the impact of COVID-19 lockdown on light
pollution.

INTRODUCTION

The COVID-19 pandemic has impacted the lives of human habits and
economic activities worldwide. Especially during the lockdown period, where
movement control order has been enforced to reduce the virality rate of the
COVID-19. The movement control order has restrict the operating business
hours of the local business, shutting down eateries, and reducing the sports
activity. Each counties has different vigour and practice in enforcing the
movement control order, each tally to the current situation of their country. As
movement control order directly ties to human activities, one can deduce that it
could impact light pollution (Bustamante-Calabria et al., 2021), which directly
relates to human health due to melatonin level, and astronomical sighting. This
provides an opportunity to study the impact of COVID-19 movement control
towards the level of light pollution and astronomical sighting.

The study of movement control order on aerosol content saw a drastic 60
percent to 31 percent decrease of nitrogen dioxide (NO2), while other air
contaminant such as sulphur dioxide (SO2), carbon monoxide (CO), ground level

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ozone (O3) also demonstrates a decrease in concentration however the decrement
are not as dominant as reduction in nitrogen dioxide. The reduction of nitrogen
dioxide in the air is important as nitrogen dioxide contribute to the severing
asthmatic symptoms, in addition to causing lung disease. Nitrogen Dioxide also
play a role in harming vegetation and discolouring furniture, causing damages in
agriculture and furniture industry. This, the reduction of nitrogen dioxide is
importance and should be continued. The main reason of nitrogen dioxide
reduction is due to the decrease of transportation traffic, as smoke from vehicles
play a major role in releasing nitrogen dioxide in the air (Fu et al., 2020; Venter et
al., 2020).

Figure 1. Reduction of Nitrogen Dioxide in the Air pre and post COVID-19
(Venter et al., 2020)

Noise pollution is a pollution in the form of noise propagation to the
degree of harmful impact. Studies on noise pollution has found a linkage between
the decrease of noise pollution, and the number of positive COVID-19 cases.
The studies that conducted on Taiwan, Boston, USA, and Dublin found a
significant reduction of noise pollution, which is primarily due to the decrease of
ground and air traffic. At city centre, the decrease of noise pollution is more
dominant as movement control order restrict the vehicle traffic from one place to
another. However location near airport and highway does not impact from
COVID-19 as traffic are still operated, although less intensive during pre-
COVID-19 era. The reduction of noise pollution is vital as noise has wide
ranging impact of human and animal. Noise pollutions impact the mating call
frequency and range of animal such as frog. Historically, frog mating call are
more frequency and can reach the range of 800 meters, however due to increase
of noise pollution, frog mating call are limited to 100 meter in range. Noise
pollution also impact human. Children who lives near the airport has found be to
suffers from stress, impairment in memory, attention level and reading skill.
Adult who excessive expose to noise pollution are likely to suffer high blood
pressure, heart diseases and stress. Thus, the reduction of noise pollution due to
COVID-19 are beneficial to both human and animal (Basu et al., 2021; Caraka et
al., 2021; Díaz et al., 2021).

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Figure 2. Reduction of Noise Pollution pre and post COVID-19
(Díaz et al., 2021)

Light pollution is a pollution the artificial lighting hampers the natural
night sky. A study of light pollution is vital as light pollution has found to impact
the regulation of melatonin in human body The lack of melatonin regulation will
cause the growth of tumour cell which eventually cause cancer. Light pollution
also found to has effect on the ecological balanced of flora and fauna. During the
COVID-19 lockdown period, it is found that light pollution has reduce during
the movement control order. Visual wavelength saw a decrease of 0.20 mag/sec2
of the sky brightness, from 18.29 mag/sec2 before movement control disorder to
18.04 mag/sec2. This mean that the sky brightness decreases by 0.5 times during
movement control order. Blue wavelength saw a significant decrease of 0.5
mag/sec2, from 19.28 mag/sec2 before the movement control order to 18.77
mag/sec2 during the movement control order. As blue wavelength light are
primarily advertisement light and private lighting, the significant decrease of blue
light demonstrates that the reduce of usage for private and advertisement lighting
(Bustamante-Calabria et al., 2021).

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Figure 3. Effect of COVID-19 on Light Pollution

While the effect of COVID-19 has a impact on urban light pollution, the
study on how the decrease of light pollution impact the visibility of moon
sighting is not study. Thus, this paper endeavor to study the impact of light
pollution on the moon sighting.

METHODOLOGY

To analyze the impact of COVID-19 lockdown on the level of light pollution, a
data monthly VIIRS satellite map from lightpollutionmap.info is collected.
Lightpollutionmap.info is a light pollution mapping website that measure the
level of light pollution using ground Sky Quality Meter measurement layered with
VIIRS satellite data. This makes the light pollution mapping by the website is
suitable for research purposes, and evidenced as it is being used for study on the
population and social impact on light pollution (Kocifaj et al., 2020; Kyba et al.,
2018), study on the impact of light pollution on insect behavior (Czaczkes et al.,
2018; Macgregor et al., 2015; van Langevelde et al., 2011), and the study of plant
physiology in response to artificial light at night (Singhal et al., 2019).

The level of light pollution is validated with another data. The level of
urban light pollution is compared with the data from (Bustamante-Calabria et al.,
2021), where the impact of COVID-19 lockdown is on urban light pollution is
analyzed. The level of light pollution on moon sighting sites is compared with the
successful rate of sighting from 2016 to 2020 on International Crescent
Observation Project database (International Crescent Observation Project, 2018).

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RESULT

Effect of COVID-19 Lockdown on Kuala Lumpur Light Pollution Level

Kuala Lumpur light pollution level has found a decrease of 0.2 mag/sec2 in the
measurement of sky brightness, from 17.219 mag/sec2 to 17.029 mag/sec2. This
means that sky brightness during the lockdown period has found a 0.5 decrease
of observable sky brightness. This will decrease of impact of sky brightness on
human health, ecological balance of insect, bird and plant. The simulation is
demonstrated in Figure 1.

Figure 4. Light Pollution in Kuala Lumpur

Effect of COVID-19 on Astronomical Sighting

The year 2020 found an increase percentage of successful moon sighting. While
in 2016 to 2019, the percentage of successful moon sighting is 53 percent, year
2020 found the percentage of moon sighting is 57 percent. This could indicate
the impact of decrease light pollution from COVID-19 lockdown to the
astronomical sighting. The percentage statistics is shown is Table 1.

Year Status of Data Percentage of Successful
Sighting Sighting
2016-
2019 Visible 508 53.08255
Invisible 449
2020
Visible 177 57.46753
Invisible 131

Total
Table 1. The Percentage statistics Moon Sighting

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CONCLUSION

The study shows the impact of COVID-19 to the light pollution of Kuala
Lumpur and moon sighting. Kuala Lumpur saw a decrease of 0.2 mag/sec2 in
term of sky brightness, while moon sighting saw a 4 percent increase of
successful sighting in 2020, from 53 percent in 2016 to 2019, to 57 percent in
2020. While the 4 percent number might be small, 4 percent in moon sighting
contribute to 50 successful moon sighting, in comparison to yesteryears.

REFERENCE

_______________________

a Akademi Pengajian Islam, Universiti Malaya Kuala Lumpur
b Akademi Pengajian Islam Kontemporari, UiTM Shah Alam
* Corresponding Author Email : [email protected]
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106

TIPOLOGI KAJIAN ILMU FALAK DI DUNIA ISLAM

Arwin Juli Rakhmadi

Abstrak: Setidaknya ada lima fokus kajian para astronom Muslim di
peradaban Islam. Lima kajian ini menjadikan astronomi (ilmu falak) di
dunia Islam demikian bernas dan berkhazanah. Lima kajian itu adalah:
instrumen astronomi, observatorium, zij, mikat, dan astrologi.
Instrumen astronomi merupakan sarana pengamatan benda langit utama
untuk mengungkap fenomena langit. Ia juga merupakan unsur penting
untuk berdiri dan beroperasinya sebuah observatorium. Dalam
perkembangannya, observatorium berfungsi dalam tiga hal penting,
yaitu sebagai pusat pengkajian langit, sebagai institusi sains, dan sarana
penentuan waktu-waktu ibadah. Zij, yang berarti tabel-tabel astronomi
hasil pengamatan dan pencatatan benda-benda langit. Zij merupakan
karya populer abad pertengahan peradaban Islam yang teradaptasi dari
tiga tradisi astronomi pra Islam. Zij sebagai tradisi populer dikalangan
astronom Muslim abad pertengahan merupakan salah satu corak tradisi
penulisan karya astronomi yang terbilang pelik, namun ia merupakan
kontribusi penting peradaban Islam. Secara historis, mikat merupakan
disiplin keilmuan Islam asli hasil akselerasi dan kreasi para astronom
muslim. Ilmu ini lahir sebagai upaya penjabaran ayat-ayat dan hadis-
hadis Nabi SAW yang menjelaskan tentang waktu-waktu salat. Entri
terpenting pembahasan mikat adalah penentuan waktu-waktu salat yang
mencakup penentuan dan perkiraan waktu terbit dan tenggelam
Matahari. Waktu-waktu salat berkaitan dengan posisi relatif Matahari
dipandang dari arah Bumi, penentuan waktu-waktu tersebut juga
bergantung pada lokasi geografis dan selalu berubah sepanjang tahun.
Variasi perubahan ini sesuai dengan perbedaan posisi garis lintang dan
garis bujur suatu tempat. Astrologi bermakna melihat keberuntungan
manusia berdasarkan pergerakan bintang-bintang di langit, orang yang
mempraktikkannya disebut astrolog. Astrologi lebih merupakan sebuah
aktifitas pengamatan gerak astronomis benda-benda langit dan kontak
planet-planet guna mengetahui hukum-hukum (perbintangan)nya
melalui acuan geraknya di alam dan fenomenanya di Bumi. Gerak
astronomis dimaksud adalah gerak peredaran tujuh benda langit populer
kala itu, yaitu Bulan, Merkurius, Matahari, Venus, Mars, Jupiter, dan
Saturnus, yang mana Bumi diasumsikan sebagai pusat alam semesta yang
beredar di sekelilingnya semua benda-benda langit.

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INSTRUMEN ASTRONOMI

Instrumen astronomi merupakan sarana pengamatan benda langit utama untuk
mengungkap fenomena langit. Ia juga merupakan unsur penting untuk berdiri
dan beroperasinya sebuah observatorium. Di peradaban Islam, instrumen
astronomi lebih berfungsi pada kepentingan praktis terkait penentuan waktu-
waktu ibadah, khususnya salat dan puasa. Dalam penentuan waktu salat, al-
Qur’an dan as-Sunnah menitahkan untuk mengamati secara terus-menerus
pergerakan Matahari di cakrawala. Pengamatan terus-menerus ini pada akhirnya
menginspirasi para ilmuwan Muslim untuk menciptakan instrumen-instrumen
tertentu guna mendeteksi pergerakan Matahari. Untuk tujuan ini maka lahirlah
instrumen yang bernam rubu mujayyab, astrolabe, mizwala, jam istiwak, dan lain-
lain. Betapapun sesungguhnya instrumen-instrumen ini telah ada sejak lama,
namun kehadirannya di peradaban Islam yang berfungsi untuk kepentingan
ibadah memiliki corak yang khas dan memiliki perbedaan signifikan pada model-
model sebelumnya.

Osama Fathi, peneliti astronomi asal Mesir, pada tahun 2014 lalu telah
melakukan penelitian berupa klasifikasi naskah-naskah instrumen astronomi yang
ada di perpustakaan Dār al-Kutub al-Mishriyyah Mesir. Penelitiannya berdasarkan
daftar-daftar naskah yang ada di Katalog Manuskrip Sains (Fihris al-Makhthūthāt
al-‘Ilmiyyah) yang disusun King. Penelitian dibatasi pada periode tertentu, yaitu
abad 8/14 sampai abad 14/20. Penelitian berupa klasifikasi jenis dan jumlah
instrumen yang ada pada tiap-tiap abad. Dari penelusurannya, Fathi mencatat
setidaknya ada 1001 naskah yang membicarakan instrumen-instrumen astronomi.
Sebanyak 605 diantaranya merupakan naskah yang teridentifikasi dimana
pengarang dan tahun penulisannya diketahui, sementara 396 naskah lainnya tidak
diketahui. Selanjutnya Fathi membagi naskah-naskah ini kepada tujuh klasifikasi,
yang mana pada masing-masing klasifikasi terdapat beberapa jenis instrumen.
Tujuh klasifikasi dan jenis-jenis instrumennya itu adalah:

1. Al-Ālāt al-kurawiyyah (instrumen bola), yaitu instrumen-instrumen
berbentuk bola dengan fungsi masing-masing. Untuk klasifikasi ini ada
empat instrumen: al-kurrah (bola, bulat), dzāt al-halq (lingkaran), al-
usthurlāb al-kurawy (astrolabe bundar), al-ālah asy-syāmilah (instrumen
komprehensif).

2. Ālāt at-tasthīh (instrumen datar) : al-usthurlāb al-musaththah asy-syimāly
(astrolabe datar), rub’ al-muqantharāt (seperempat lengkung), ar-rub’ al-
kāmil (seperempat sempurna), ar-rub’ al-hilāly (seperempat bulan sabit),
tsumun ad-dā’irah (seperdelapan lingkaran), dan al-musātirah.

3. Arba’ hisāb al-mutsallatsāt (kuartal aritmetika segi tiga bola) : ar-rub’ al-
mujayyab (rubu mujayyab), ar-rub’ al-mujannah (seperempat bersayap), al-
jaib al-ghā’ib (lubang hilang), ar-rub’ at-tāmm (seperempat sempurna), al-
murabba’ah (persegi empat).

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4. Al-Ālāt asy-syāmilah li jāmī’ al-‘urudh (instrumen komprehensif untuk semua
lintang) : az-zarqalah (arzachel), asy-syakāziyah (syakkaziya), al-ālah al-
jāmi’ah (instrumen universal), muqantharāt khath al-istiwā’ (lengkung
katulistiwa), ar-rub’ asy-syakāzy (seperempat syakkaziya), ar-rub’ al-jāmi’
(seperempat universal), dan ālah as-saraj/as-sarajiyyah (instrumen Ibn
Saraj).

5. Ālah ar-rashd (instrumen observasional) : dzāt asy-syu’batain (instrumen
bercabang), al-mistharatain (dua penggaris), al-birkār at-tāmm (jangka
sempurna), ālah al-ab’ad (instrumen pengukuran), dan ash-shafīhah al-
qamariyyah (lempeng bulan).

6. Ālah al-qiblah (instrumen kiblat) : dā’irah al-mu’addal (lingkaran paralel),
dā’irah al-mahārīb (lingkaran mihrab), bait al-ibrah (rumah jarum, kompas),
dan al-muqawwar.

7. Al-mazāwil (mizwala).

Beberapa Instrumen Populer Abad Pertengahan: Mizwala, Astrolabe,
Rubu Mujayyab, Kompas (al-Būshlah), Rubu Sempurna (Rub’ Tāmm), Rubu
Bersayap (Rub’ Mujannah), Rubu Lengkung (Rub’ Muqantharāt), Rubu Sempurna
(Rub’ Kāmil), Rubu Hilal (Rub’ Hilāly), Al-Musātirah, Jaib al-Ghā’ib, Persegi Empat
(al-Murabba’ah), Lempeng Zarqali (Shafīhah Zarqāliyyah), Al-Syakāziyyah, Rubu
Syakazi (Rub’ Syakāzy), Instrumen Ibn Saraj (Ālah Ibn al-Sarāj), Lingkaran (Dzāt al-
Halq), Al-Syāmilah, Libnah, Lingkaran Ekuatorial (Halqah I’tidāliyyah), Dzāt al-
Tsuqbatain, Bola Langit (Kurrah Samāwiyyah), Kotak Waktu (Shundūq al-Yawāqit),
Torquetum (Dzā al-Samt wa al-Irtifā’), Dzāt al-Autār, al-Musyabbahah bi al-Manāthiq,
Ekuatoria (Thabaq al-Manātiq), Lingkaran Ufuk Komprehensif (al-Halqah al-
Ufuqiyyah al-Syāmilah), Sekstan Fakhri (Suds Fakhry), Sekstan (Sudsiyyah).

OBSERVATORIUM

Observatorium dalam bahasa Arab disebut al-marshad (jamak: al-marāshad),
sedangkan dalam bahasa Inggris disebut observatory. Al-marshad berasal dari
kata ar-rashd. Dari makna literernya dapat difahami bahwa rashd berarti observasi,
sedangkan marshad berarti tempat observasi atau observatorium. Dalam
khazanah intelektual Islam klasik, observatorium disebut juga dengan ar-rashd,
dār ar-rashd dan bait ar-rashd. Secara terminologis, observatorium adalah
sebentuk bangunan tempat dimana dilakukan pengamatan benda-benda langit
yang mana pengamatan tersebut tercatat. Observatorium sangat identik dengan
instrumen-instrumen yang beragam disamping lokasi tempat beradanya yang
strategis. Dalam konteks moden, observatorium dapat dinyatakan sebagai warisan
sekaligus sumbangan yang teramat berharga dari peradaban Islam. Menurut Nasr,
observatorium sebagai sebuah institusi ilmiah merupakan kontribusi orisinal
peradaban Islam. Di lembaga ini pengembangan astronomi dan ilmu-ilmu
berkaitan berlangsung dengan giat pada abad pertengahan.

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Dalam perkembangannya, observatorium berfungsi dalam tiga hal:
pertama, sebagai pusat pengkajian langit. Kedua, sebagai institusi sains. Ketiga,
sarana penentuan waktu-waktu ibadah. Beberapa observatorium di dunia Islam:
Observatorium Qasiyun, Observatorium Banu Musa, Observatorium al-Dinawari
(Observatorium Ishfihan), Observatorium al-Battani, Observatorium Syaraf ad-
Daulah, Observatorium al-Afdhal al-Bathā’ihy, Observatorium Ibn A’lam,
Observatorium ‘Alā’ ad-Daulah, Observatorium Malik-Syah, Observatorium
Maragha, Observatorium Samarkand, Observatorium Istanbul.

ZIJ

Zij berarti tabel-tabel astronomi hasil pengamatan dan pencatatan benda-benda
langit. Zij merupakan karya populer abad pertengahan peradaban Islam yang
teradaptasi dari tiga tradisi astronomi pra Islam: Persia, Yunani, dan India. Dari
tradisi Persia melalui Zij Shahriyar, dari tradisi India melalui Sindhind, dan dari
tradisi Yunani melalui Almagest. Data-data yang terdokumentasi dalam sebuah
zij umumnya adalah data gerak dan posisi benda-benda langit tertentu sesuai
keinginan pembuatnya. Benda-benda langit yang umum didokumentasikan adalah
Saturnus, Jupiter, Mars, Venus dan Merkurius, disampig Bulan dan Matahari.
Data-data benda langit ini tersusun dalam standar jam, derajat, menit dan detik
yang ditulis secara teratur dan berurutan. Data-data ini diperhitungkan dalam
gerak harian, bulanan dan tahunan. Untuk menggambarkan pencatatan dan
pengamatan itu umumnya para pembuat zij–yang secara otomatis seorang
astronom–menggunakan istilah-istilah tertentu, seperti “al-khāsshah” yaitu jarak
busur sepanjang ekliptika sampai titik aries, “al-wasath” yaitu busur sepanjang
ekliptika dari bulan hingga aries, “al-markaz” yaitu busur sepanjang ekliptika dari
Matahari sampai aries, aphelion (al-auj) yaitu titik terjauh suatu benda langit dari
Matahari, perihelion (al-hadhīdh) yaitu titik terdekat suatu benda langit dari
Matahari (kebalikan perihelion), dan lain-lain.

Zij sebagai tradisi populer dikalangan astronom Muslim abad pertengahan
merupakan salah satu corak tradisi penulisan karya astronomi yang terbilang pelik,
namun ia merupakan kontribusi penting peradaban Islam. Tradisi zij sendiri di
dunia Islam telah berlangsung selama seribu tahun lebih. Menurut King, tradisi zij
bermula di Bagdad era Abbasiyah, selanjutnya berkembang pesat di Cairo era
Fatimiyah, hingga akhirnya meredup di era Ottoman, Turki. Di dunia Islam abad
pertengahan, zij merupakan dasar dan perangkat penomoran (numerical tables)
yang digunakan oleh para astronom dan astrolog untuk mengukur dan
menghitung peredaran dan posisi benda-benda langit. Dalam praktiknya, angka-
angka numerik benda-benda langit dalam bentuk zij ini disusun berdasarkan
sejumlah observasi berkelanjutan yang dilakukan oleh para pengkaji dan
pengamat langit. Observasi ini sendiri umumnya dilakukan di sebuah
observatorium resmi yang difasilitasi oleh penguasa dimana tersedia alat-alat
observasi yang memadai. Selain itu, ada juga pengamatan dan pencatatan terhadap
gerak dan posisi benda-benda langit yang dilakukan tanpa menggunakan alat-alat

110

tertentu, namun hanya berdasarkan observasi indrawi. Pengamatan dan
pencatatan numerik ini juga dilakukan oleh pengamat-pengamat independen
(baca: pribadi)–yang tetap terdokumentasi dan mengikuti aturan yang ada–seperti
dilakukan Ibn Majdi (w. 850/1446) dalam zijnya yang bertitel “ad-Durr al-Yatīm
fī Shinā’ah at-Taqwīm” (Permata Tentang Pembuatan Kalender).

Arti penting tabel-tabel astronomi (zij) bagi pengamat dan pencatat gerak
dan posisi benda-benda langit zaman dahulu adalah sebagai data verifikasi
sekaligus perbandingan observasi antara satu generasi zij dengan generasi zij
berikutnya. Selanjutnya melalui data-data ini dapat dirumuskan gambaran
mengenai benda-benda langit secara lebih presisi, yang dalam perkembangannya
juga terus diperbarui. Seperti dikemukakan Ibn Khaldun, penyusunan sebuah zij
dalam bentuk tabel-tabel adalah dalam rangka membantu dan memudahkan para
pengkaji langit pemula (al-muta’allimīn), meski pada kenyataannya pengkaji
profesionalpun mengambil manfaat dari data-data ini. Arti penting zij dalam
konteks modern adalah cikal bakal lahirnya apa yang dikenal dengan alamanak
dan atau ephemiris. Misalnya, “Ephemiris Hisab Rukyat” yang rutin dikeluarkan
setiap tahun oleh Kementerian Agama RI dan “ad-Dalīl al-Falaky” yang rutin
diterbitkan setiap tahun oleh “National Research Institute of Astronomy and
Geophysics” (NRIAG) Helwan, Mesir. Keduanya ini dapat dinyatakan sebagai
bentuk konkret zij kreasi astronom Muslim dari zaman silam. Sementara itu
dalam kepentingan praktis sehari-hari, arti penting zij adalah lahirnya kalender
dinding tahunan dan buku agenda yang memuat data-data (momen) suatu
peristiwa setiap tahun.

Beberapa Zij Populer di Dunia Islam:

 Zij al-Khawārizmī : al-Khawarizmi (w. 232/848)

 Zij Ibn al-A’lam : Ibn A’lam (w. 375/985)
 Zij Abu Ma’syar : Abu Ma’syar al-Balkhy (w. 272/885)
 Zij ash-Shāby’ : al-Battani (w. 317/929)
 Zij al-Hākimy al-Kabīr : Ibn Yunus (w. 399/1009)
 Zij al-Jadīd : Ibn Syathir (w. 777/1375)
 Ad-Durr al-Yatīm fī Shinā’ah at-Taqwīm : Ibn Majdi (w. 850/1446)
 Zij Ilkhāny : Nashiruddin al-Thusi (w. 672/1274)
 Zij Jadīd Sulthāny : Ulugh Bek (w. 853/1449)

MIQAT
Dalam sintaksis bahasa Arab, kata mīqāt (al-mīqāt) terderivasi dari kata al-waqt
(waktu). Kata mawāqīt–bentuk jamak dari mīqāt–tertera dan digunakan dalam al-
Qur’an di beberapa tempat, antara lain QS. al-Baqarah [02]: 189 , QS. an-Naba’
[78]: 17 , QS. al-A’raf [07]: 142 , QS. ad-Dukhan [44]: 40 , dan QS. an-Nisa’ [04]:
103 . Oleh karena itu dapat dinyatakan bahwa penggunaan terminologi mikat
sesungguhnya terinspirasi dari al-Qur’an. Terminologi mīqāt telah populer

111

dikalangan astronom Muslim abad pertengahan. Bahkan dalam perkembangannya
ilmu ini menjadi disiplin ilmu mandiri yang berbeda dengan ilmu zij dan observasi
yang telah berkembang saat itu, meskipun dalam tataran hierarkisnya ilmu ini
tetap berada dibawah rumpun astronomi.

Dalam sejarah abad pertengahan, ulama yang menekuni bidang ini dikenal
dengan sebutan “muwaqqit” atau “mīqāty” yang secara bahasa berarti ‘juru
waktu’. Dalam konteks zaman itu, muwaqqit lebih didefinisikan sebagai seorang
astronom profesional yang menguasai dasar-dasar astronomi bola dan
matematika yang berafiliasi kepada salah satu masjid atau institusi keagamaan
yang mana tugas pokoknya menentukan waktu-waktu salat. Bahkan menurut Hill,
profesi ini difasilitasi oleh penguasa. Selain itu ada juga muwaqqit yang menekuni
bidang ini namun tidak berafiliasi sama sekali kepada suatu mesjid atau institusi
keagamaan.

Bila diperhatikan, dalam sejarah awal kemunculannya, mikat
sesungguhnya lebih mengkaji waktu-waktu salat. Seperti di deskripsikan King,
mikat merupakan cabang astronomi berkaitan pengaturan waktu-waktu salat
(timekeeping) berdasarkan rotasi harian Matahari dan bintang-bintang untuk
menentukan waktu pada siang hari maupun malam hari dengan cara menerapkan
rumusan trigonometri pada data yang berasal dari pengamatan posisi Matahari
dan bintang-bintang. Namun seiring perjalanan waktu cakupan ilmu ini meluas
dengan kajian-kajian lain yang terkait rotasi harian Matahari dan benda-benda
langit yaitu penentuan arah kiblat (Mekah), penentuan awal bulan, penentuan
gerhana dan lain-lain.

Secara historis, mikat merupakan disiplin keilmuan Islam asli hasil
akselerasi dan kreasi para astronom muslim. Ilmu ini lahir sebagai upaya
penjabaran ayat-ayat dan hadis-hadis Nabi SAW yang menjelaskan tentang waktu-
waktu salat. Seperti diketahui, waktu-waktu salat yang dipraktikkan baginda Nabi
SAW bersama malaikat Jibril sangat bergantung pada posisi harian Matahari dari
waktu ke waktu. Dari perspektif ini, mikat sebenarnya telah ada dan dipraktikkan
oleh baginda Nabi SAW, sahabat dan generasi-generasi berikutnya. Oleh karena
itu dapat dinyatakan bahwa mikat di peradaban Islam merupakan cabang
astronomi baru dan memiliki posisi penting dalam Islam karena berhubungan
dengan persoalan ibadah. Ilmu ini dibangun oleh para astronom Muslim dengan
nama baru yaitu “ilmu mikat” (‘ilm al-mīqāt) guna mengurai problematika
pewaktuan ibadah dalam agama (Islam).

Entri terpenting pembahasan mikat adalah penentuan waktu-waktu salat
yang mencakup penentuan dan perkiraan waktu terbit dan tenggelam Matahari.
Waktu-waktu salat berkaitan dengan posisi relatif Matahari dipandang dari arah
Bumi, penentuan waktu-waktu tersebut juga bergantung pada lokasi geografis dan
selalu berubah sepanjang tahun. Variasi perubahan ini sesuai dengan perbedaan
posisi garis lintang dan garis bujur suatu tempat. Dalam praktiknya lagi, mikat
sangat terkait dengan konsepsi astronomi bola (al-falak al-kurawy, spherical
astronomy) dan trigonometri (hisāb al-mutsallatsāt) yang menjadi dasar

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konstruksi mikat. Dua konsepsi ini menjadi dasar praktis dan selanjutnya menjadi
populer dikalangan astronom Muslim era awal yang bersumber dari sumber-
sumber India.

Pendefinisian waktu-waktu salat pada masa Nabi SAW dan era awal Islam
hanya mengandalkan observasi langsung, dan dalam kenyataannya penentuan
waktu salat tidak dengan mudah dapat dilakukan. Satu-satunya cara untuk
memastikan tibanya waktu salat adalah dengan mengamati Matahari dan atau
bintang-bintang di langit. Kondisi ini mendorong umat Islam dan terutama para
astronom Muslim zaman itu merumuskan penentuan waktu salat secara
matematis. Ehsan Masood dalam “Science and Islam a History” mendeskripsikan
praktik matematis penentuan waktu salat ini. Ia menjelaskan bahwa praktik itu
dilakukan pada mulanya dengan menentukan sudut yang tidak diketahui pada
sebuah segitiga besar antara bumi dan langit dari sudut yang sudah diketahui.
Pada salah satu sudut segitiga itu terletak suatu titik bintang tertentu. Di sudut
lainnya adalah kutub langit utara yang dikelilingi bintang-bintang yang berotasi.
Sudut berikutnya adalah zenit, yaitu titik tertinggi yang bisa dicapai bintang yang
muncul di malam hari. Praktik ini–menurut Masood–mendorong berkembangnya
perhitungan astronomi dan matematika trigonometri ke tingkat yang lebih tinggi.
Praktik ini juga mendorong lahirnya temuan-temuan alat penentu sudut yang
telah eksis sejak era Yunani yaitu astrolabe.

ASTROLOGI
Astrologi dalam bahasa Arab disebut at-tanjīm atau an-nujūm, keduanya
bermakna bintang. Fairuz Abadi (w. 817/1414) menyebutkan beberapa diksi
astrologi yaitu al-minajjim, al-mutanajjim, dan an-najjam, yang bermakna melihat
bintang-bintang berdasarkan waktu dan perjalanannya. Astrologi juga berasal dari
akar kata najjama-yunajjimu-tanjīman, yang secara etimologi bermakna ‘limit
batas’. Disebut demikian karena orang-orang Arab dahulu menjadikan posisi
(manzilah) terbit dan tenggelam Bulan sebagai limit batas membayar hutang.
Sementara munajjim atau tanajjum adalah orang yang melihat dan menghitung
waktu peredaran Bulan dan atau bintang-bintang tersebut.

Dalam literatur Arab klasik, ada ragam terminologi astrologi, antara lain:
astrologi (at-tanjīm), ilmu nujum (‘ilm an-nujūm), kreasi perbintangan (shinā’ah
an-nujūm), dan ilmu hukum-hukum perbintangn (‘ilm al-ahkām). Terminologi
terakhir (ilmu hukum-hukum perbintangan) ini dimaksudkan sebagai astrologi di
era modern yaitu upaya mencari petunjuk berdasarkan formasi dan posisi
astronomis benda-benda langit terhadap kejadian yang terjadi di alam. Sedangkan
obyeknya adalah planet-planet (benda-benda langit) dengan segenap bagian-
bagiannya. Penambahan kata ‘perbintangan’ dimaksudkan untuk membedakan
dengan astronomi (hai’ah, falak) yang populer di peradaban Islam.

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Terminologi astrologi (at-tanjīm) sejatinya bukan istilah baru, istilah ini
telah populer dalam khazanah klasik yang tidak hanya terbatas digunakan pada
astrologi semata namun pada astronomi observasional secara bersamaan. Namun
demikian terdapat penamaan klasik dan terbatas pada aspek non ilmiah yaitu apa
yang disebut dengan ilmu hukum-hukum (‘ilm al-ahkām) atau ilmu hukum-
hukum perbintangan (‘ilm ahkām an-nujūm) atau ilmu perbintangan al-ahkami
(‘ilm an-nujūm al-ahkāmy). Istilah-istilah ini berhadapan secara diametral dengan
aspek ilmiah sains yang mengkaji langit yaitu ilmu astronomi (‘ilm al-hai’ah).

‘Ilm al-ahkām adalah penamaan terpopuler yang berkembang terhadap
astrologi di era peradaban Islam, selain ada penamaan lain seperti ‘ilm an-nujūm,
‘ilm shinā’ah an-nujūm, dan ‘ilm shinā’ah at-tanjīm. Hanya saja istilah-istilah ini
bercampur antara aspek astronomi dan astrologinya. Ada lagi penamaan lain
datang belakangan yang digunakan dalam literatur-literatur Arab sejak abad 13 M
yaitu ‘ilm an-najāmah yang menunjukkan orientasi astrologi.

Secara terminologis, astrologi bermakna melihat keberuntungan manusia
berdasarkan pergerakan bintang-bintang di langit, orang yang mempraktikkannya
disebut astrolog. Astrologi lebih merupakan sebuah aktifitas pengamatan gerak
astronomis benda-benda langit dan kontak planet-planet guna mengetahui
hukum-hukum (perbintangan)nya melalui acuan geraknya di alam dan
fenomenanya di Bumi. Gerak astronomis dimaksud adalah gerak peredaran tujuh
benda langit populer kala itu, yaitu Bulan, Merkurius, Matahari, Venus, Mars,
Jupiter, dan Saturnus, yang mana Bumi diasumsikan sebagai pusat alam semesta
yang beredar di sekelilingnya semua benda-benda langit.

Namun patut diperhatikan, seperti telah ditegaskan di atas, penggunaan
istilah at-tanjīm (astrologi) di abad pertengahan adakalanya bermakna ganda, di
satu sisi dimaknai astrologi, namun di sisi lain dimaknai astronomi. Bahkan
keduanya terkadang dimaknai secara bersamaan tanpa ada pembedaan.
Pembedaan itu secara jelas dan tegas baru terjadi memasuki abad 19 M.

RUJUKAN

_______________________

* Universitas Muhammadiyah Sumatera Utara. Email: [email protected]
[1] Osama Fathi, Makhthūthāt al-Ālāt al-Falakiyyah fī Dār al-Kutub al-Mishriyyah,
dalam “Majallah Ma’had al-Makhthūthāt al-‘Arabiyyah” (edisi 58, j. 1, 1435/2014)
[2] Abdul Amir al-Mu’min, Qāmūs Dār ‘Ilm al-Falaky (Beirut: Dār al-‘Ilm li al-
Malāyīn, cet. I, 2006
[3] David A. King, Zidj, dalam “ The Encyclopaedia of Islam ” , vol. XI
(Leiden-New York: E.J. Brill, 1993)

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[4] David A. King, ‘Ilm al-Mīqāt fī Suriyah Khilāl al-Qarn ar-Rābi’ ‘Asyara, dalam
“Abhāts an-Nadwah al-‘Alamiyah al-Ūlā li Tārīkh al-‘Ulūm ‘Inda al-‘Arab”
(Aleppo: Universitas Aleppo, 1396/1976)
[5] David A. King, Mikat, dalam “The Encyclopaedia of Islam”, vol. VII
(Leiden-New York: E.J. Brill)
[6] David A. King, The Astronomy of The Mamluks, dalam “ Islamic
Mathematical Astronomy” (London: Variorum Reprints, 1986)
[7] David A. King, ‘Ilm al-Mīqāt fī Suriah Khilāl al-Qarn ar-Rābi’ ‘Asyara, dalam
“Abhāts an-Nadwah al-‘Alamiyyah al-Ūlā li Tārīkh al-‘Ulūm ‘Inda al-‘Arab”
(Aleppo: Ma’had at-Turāts al-‘Ilmy al-‘Araby, 1977)
[8] Donald R. Hill, al-‘Ulūm wa al-Handasah fī al-Hadhārah al-Islāmiyyah,
Terjemah: Dr. Ahmad Fuad Bāsyā (Kuwait: ‘Ālam al-Ma’rifah, 2004 M)
[9] Dirasah atas naskah “Ghunyah al-Fahīm wa ath-Tharīq Ilā Hall at-Taqwīm”
karya Ahmad bin Rajab al-Majdi (w. 850/1446), Tahkik: Arwin Juli Rakhmadi
Butar-Butar (Cairo: Ma’had al-Makhthuthāt al-‘Arabiyyah, Tesis, 2009)
[10] Ehsan Masood, Ilmuwan-Ilmuwan Muslim Pelopor Hebat di Bidang Sains
Modern, Terjemah: Fahmy Yamani (Jakarta: PT. Gramedia Pustaka Utama, 2009)
[11] Muhammad bin Ya’qub al-Fairuz Abadi, al-Qāmūs al-Muhīth, j. 4 (Beirut: al-
Mu’assasah al-‘Arabiyyah li ath-Thibā’ah wa an-Nasyr, t.t.)

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116

ISLAMIC ASTRONOMY IN TURKEY

Ümit Ertem

Abstract: Islamic Astronomy applications for religious time calculations
in Turkey are provided by the Presidency of Religious Affairs. The three
main topics of Islamic astronomy are prayer time calculations,
determination of the beginning of the lunar calendar and calculating
qiblah directions for mosques and other places. We provide daily prayer
times, ramadan prayer times and eid prayer times of more than 8600
places all around the world. We calculate fajr times according to the
Sun’s altitude of -18 degrees and isha times according to the Sun’s
altitude of -17 degrees. Sunrise and sunset times are calculated with
additions due to the altitudes and widths of places. The beginning of the
lunar calendar is determined by the observation of the first crescent
from any place around the world. We provide crescent visibility maps of
the world for the periods of ten years. Crescent visibility criteria are
considered as 8 degrees elongation of the Moon according to Sun and 5
degrees altitude of the Moon when the Sun sets. These criteria are based
on the decisions accepted at the International Lunar Calendar
Conferences held in Istanbul in 1978 and 2016. We also calculate qiblah
times and qiblah angles of the places in the world and determine the
qiblah angles of local places according to the Sun’s position at qiblah
times. All of those information about Islamic Astronomy calculations is
published at the website https://vakithesaplama.diyanet.gov.tr/ and
more information can be requested via the corresponding e-mail
addresses.

INTRODUCTION

In present Presidency of Religious Affairs, we have Time Calculation Branch
includes a few Astronomers, a few Time Calculation Experts and some Religious
Experts. Together, we performed Islamic astronomy studies in Turkey. There are
three branches in Islamic Astronomy which are prayer times, lunar months, and
qiblah times and directions. We also calculate prayer times, lunar months and
qiblah times and angles for every city in the world. So, I will give details on how
to calculate prayer times, lunar months, and qiblah times, and which criteria we
use for these calculations.

PRAYER TIMES

We need to determine Astronomical criteria for prayer times. To find the correct
prayer times we need to consider the Positions of the Sun at the celestial sphere
at Fajr, sunrise, Zuhr, Asr, Maghrib and Isha times. Zuhr Time: Zuhr prayer time

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starts when the Sun passes the meridian and inclines towards west. We calculate
the meridian passing time and add 5 minutes to calculate the Zuhr time. Second
prayer time is Asr. There two versions of Asr time; First Asr and Second Asr.
The First Asr correspond to the shadow of an object is equal to its meridian-pass
shadow plus its own length. For Second Asr, the time starts when the shadow of
an object is equal to its meridian-pass shadow plus two times of its own length.
For the Calendar, we calculate the First Asr and add 4 minutes.

Figure 1. We calculate the first asr and add 4 minutes to use it in calendars

Sunrise time: It starts when the upper limb of the Sun appears over the
horizon even when observed from the lowest site of the district, because during
sunrise, the sunlight is reflected to the opposite direction, namely to the west.

For third prayer times we consider Maghrib time: It starts when the upper
limb of the Sun disappears under the horizon even when observed from the
highest site of the district, because during sunset, the sunlight is reflected to the
opposite direction, namely to the east. One also must consider the refraction
effects for Maghrib time.

Hour angle of the center of the 90 °00’
sun

Refraction index 00° 34’

Sun’s radius 00° 16’

Total 90° 50’

90°.833

Table 1. Refraction angle; apparent sun elevation angle-true sun elevation angle

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As we can see in Figure 2 is the observer, when true sun disappears under
horizon, the apparent sun can be see above the horizon because of the refraction
effect. So, we have to consider refracting effect to calculate Maghrib time. To
consider different heights and widths of cities, we calculate the sunset time and
add 7 minutes to use it in Calendars.

Figure 2. To consider different heights and widths of the cities, we calculate the
sunset time and add 7 minutes to use it in calendars

Next prayer times is Isha: Isha time begins when the twilight (dusk)
disappears over the horizon. It depends on the scattering of the sunlight along
the atmosphere. Hence, it depends on atmospheric conditions such as
temperature, humidity, pressure, etc. Our criteria for Isha time after observations
and as traditions, we consider the beginning of Isha time when the Sun is 17°
below horizon.

Fajr prayer time: Fajr time starts when the true dawn appears over the
horizon. It corresponds to the beginning of astronomical twilight. Astronomical
twilight appears when the Sun is between 12° and 18° below the horizon. Below
18°, the sky illumination is so faint that it is practically dark. We consider the
beginning of fajr time when the Sun is 18° below horizon.

1. Fajr Sun altitude 18°

(No additional time margin)

Hour angle of the center of the sun
90 °00’

Refraction index
00° 34’

2. Sunrise and Maghrib Sun’s radius
00° 16’

Total
90°50’

90°.833
Additional margin 7 min

3. Dhuhr Sun’s Transit time + 5 min

4. Asr Time of correct shadow leght + 4 min

5. Isha Sun altitude -17°
(No additional time margin)

Table 2 Summary Criteria for Prayer Times Presidency of Religious Affairs

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We also calculate Eid Prayers: We consider the beginnings of Eid Prayers
when the Sun is 5° above the horizon after sunrise.
FAJR AND ISHA OBSERVATIONS
Presidency of Religious Affairs has organized Fajr and Isha observations in
different places and different times. For example, we have observed Fajr and Isha
in Gerede district of Bolu, Turkey in 28-30 September 2019. The observers
include Astronomers Presidency of Religious Affairs, High Board of Religious
Affairs Members and Religious Representatives from Europe. From these
pictures 18° is to confirm Fajr time starts.

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Figure 3. Picture Subh Observations
We are also make observation of Fajr and Isha times with all Sky camera (ASC) at
Eastern Anatolian Observatory, Erzurum-Turkey.

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Figure 4. Instrument for Fajr and Isha observation

Figure 5. Picture of Isha Time Observation Using ASC
EXTREME LATITUDES AND VANISHING PRAYER TIMES
We can divide the earth into three zones, regarding the formation of the seasons
and the variation of day/night durations. The latitudes between ± 23°.4, the
latitudes above ± 66°, and the latitudes between 23°.4 and 66° for both
hemispheres.

• The equatorial zone between ± 23.4° latitudes:
The Sun tracks a near-vertical trajectory, therefore the

lengthening/shortening of the daytime during summer/winter is not prominent
so the four seasons cannot be distinguished, and a tropical climate exists all the
year.

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Figure 6. Summer and winter trajectories of the Sun in Mecca
• Polar zone with latitude greater than ±66°:

The Sun will follow a rather horizontal trajectory. The durations of the
day and the night exhibit great difference in winter and summer. In some days
near solstice, the Sun will not even rise nor set. Thus, on polar locations, some of
the daily prayer timings or even all of them will not occur astronomically.

Figure 7. Summer and winter soltices trajectory of the Sun in Oslo
• The region between these extreme zones:
The daytime prolongs/shrinks in summer/winter period depending on the
latitude. At higher latitude, the Sun moves more horizontally, so the night
duration in summer will be shorter, which causes the Isha and Fajr timings to
approach each other. This poses a difficulty to perform the Isha prayer, since it
is squeezed into a late and small time. Above ±45° latitudes, Fajr and Isha prayer

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times will disappear on some days during the year. Above ±66° latitudes, sunrise
and sunset times will also disappear on some days during the year. Moreover, on
some days, those prayer times will be impractical to apply even though they
appear.

The criteria of Presidency of Religious Affairs for the prayer times of
latitudes between ±45° and ±64° : Isha time will be found by adding 80 minutes
to maghrib time during all year. 80 minutes corresponds to the average time
difference between Maghrib and Isha times in Mecca during the year. Fajr time
will be found by subtracting 90 minutes from the sunrise during the summer
season, and transforming to the real Fajr times during the spring and autumn
seasons.

The criteria of Presidency of Religious Affairs for the prayer times of
latitudes above ±64°: all prayer times are calculated by taking the latitude as ±64°
and by taking own longitude of the place. We are currently studying on the
improvements of those criteria for extreme latitudes. There will be a conference
on prayer times criteria for extreme latitudes on 26-27 September in Istanbul with
the participation of Presidency of Religious Affairs and other religious authorities
in Europe.
LUNAR MONTHS
Beginnings of Lunar Months
The lunar month starts on the evening when the crescent is first observed in the
sky. So, the definition of the beginning of an Islamic month is the actual
observation of the new crescent on the west horizon after sunset, upon which the
1st day of the new lunar month begins. A lunar month has a length of either 29
or 30 days. The Moon moves around the earth in counter-clockwise direction
and completes one turn in 27.3216 days. This period, referenced again to a very
distant star, is named as the sidereal month. Since the Moon rotates around itself
with the same speed as around the Earth, always its same side is visible from the
Earth. But the Moon also rotates around the Sun together with the Earth. Since
the Moon is not a light source and it only reflects the rays from the Sun, its shape
or visibility will depend upon the position relative to the Sun. Therefore, one full
lunation, as seen from earth, will be equal to the period of one complete turn
around the Earth when observed from the Sun. This period from one
conjunction to the next, is named as synodic month and has an average duration
of 29.5306 days.

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Figure 8. Sidereal and Synodic Months
Since the Moon's orbit is rather elliptic, its rotational speed changes in
time and one synodic month may alter between 29.27 and 29.84 days. That's the
reason a lunar month can be either 29 or 30 days. The angle between the sun-
earth line and the projection of the Moon on the ecliptic plane is defined as the
Moon phase angle. It is 0º at conjunction, 90º at first quarter, 180º at full-moon
and 270º at last quarter.

Figure 9. Moon Declination
Visibility Criteria and Calculations
A lunar month starts astronomically when the Sun-Earth line coincides with the
Earth-Moon line projected onto the ecliptic plane, which is named as
conjunction. Since the religious condition for the lunar month to begin is that the
new crescent must be observed, the Moon has to separate a certain distance from
the point of conjunction such that the sunlight reflected from its edge (crescent)
can reach the Earth.

Figure 10. Conjunction and earliest visibility

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In order an observer's eye to distinguish the very first crescent on the sky,
it must attain a certain thickness. The amount of the necessary thickness depends
on the contrast, i.e., the ratio between the brightness of the moon and the
brightness of surrounding sky. We may see a thinner crescent in a darker sky,
which is the case during sunset. Nevertheless, in the waxing crescent phase, the
Moon follows the Sun just from behind such that the Moon sets soon after the
Sun. This means that the earliest crescent can be visible within a rather short
period (several minutes). So, we need a criterion for the first visibility of the
crescent depending on the separation angle between the Sun and the Moon,
altitude of the Moon when the Sun sets.

Moreover, the moonsighting may be divided into three categories, namely
local, regional, or global. Local sighting requires that the crescent is actually
witnessed on the district; every region depends on its own observation and the
start date of a month may differ among the countries (ikhtilaf-ul-matali'). For this
opinion, a crescent visibility map based on some visibility criteria will estimate the
start of a lunar month for any local position.

Regional sighting, on the other hand, accepts that if authentic
moonsighting news comes from neighbour areas, then local sighting is no more
determinative (ittihad-ul-matali'). The wide interpretation of this thought is the
global moonsighting; if the New Moon has been attested in any location of the
world, then all the rest will accept the start of the month. Under this admission,
an International Hijri Calendar could be established.

Presidency of Religious Affairs also considers the decisions of the
International Hijri Calendar Union Congress held in 2016 in Istanbul for the
calculation of the beginnings of lunar months. The fundamental principle for the
determination of the beginning of the lunar month is the sight of the crescent
either by naked eye or by modern astronomical devices. The sight of the crescent
at different times in different places is not considered and that the crescent is
seen everywhere when it is seen in one place (ittihad-ul-matali') is approved. The
congress preferred the unique calendar to apply all around the world. Thus, there
will be only one Hijri calendar for everyone. According to this, the following
criteria is used for the calculation of the beginnings of the lunar months:

Firstly - It is adopted that the sight of the crescent is possible when the moon’s
elongation (separation angle) is 8º and the moon’s altitude is 5º when the sun is
set. If one of these criteria is not realized, then it is not possible to see the first
crescent by the naked eye.

Secondly - When the crescent is seen according to the Greenwich time, the time
of conjunction must be before the Fajr time in Australia and New Zealand.

Thirdly - When the crescent line appears, the crescent must be seen from the
lands in the American Continent.

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Based on those criteria, we calculate the crescent visibility maps for the
World. And determine the beginnings of lunar months.

Figure 11. Crescent visibility maps.

Table 3. Crescent visibility observations all around the world
Our represtatives from different cities in Turkey and all around the world
also make crescent observations in Ramadan, Shawwal and Zilhijjah months and
send us the picture of the first crescent. Moreover, we also make crecent
observation in AYGÖZ project with CCD cameras:
1 -QSI CCD Camera
2 -The Imaging Source Camera

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Figure 12. At TÜBİTAK National Observatory in Antalya-Turkey

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Figure 13. Crescent observation with CCD Camera

QIBLA
Qibla Angle
Qibla angle is defined as the horizontal angle between the Kaaba direction and
the geographic north, which is determined by spherical trigonometry formulas.
Qibla Time
When the Sun is at the meridian of Kaaba, the Sun’s direction will give the qibla
direction for any place on the Earth. This meridian transit time is called as Qibla
Time. So, we can determine the qibla direction by calculating Qibla Time and
finding the Sun’s position at this time. One can also use magnetic compasses to

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determine qibla directions. However, in that case, one must consider magnetic
declinations for every place on Earth, since the magnetic North and geographical
North differs from one another.

Figure 14. Earth magnetic declination map.
Finding the Sun’s position at Qibla Time gives more definite results for
the qibla directions and we use this method to find qibla directions of local
mosques.
WEBSITES
All those information can be found at our website vakithesaplama.diyanet.gov.tr.
We also provide the prayer times of 8600 cities from 206 countries all around the
world at the website namazvakitleri.diyanet.gov.tr.

Figure 15. Website for prayer times in Turkey

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ISLAMIC ASTRONOMY IN THE 21ST CENTURY

Nidhal Guessoum, American University of Sharjah, UAE

Abstract

First, what is Islamic astronomy? If we adopt Morrison’s simple definition that
“’Islamic astronomy’ designates the astronomy of Islamic civilization”5 (rulers
and/or populations), then it becomes instructive to ask: What characterized
‘Islamic astronomy’ during the golden age of the Islamic civilization, and what
lessons can be drawn from that extended and rich period as we look forward into
the 21st century and beyond? Classical (i.e. medieval or ‘golden age’) Islamic
astronomy included astronomy of Islamic practices (‘cIlm al-Falak al-Sharciy’), i.e.
the determination of the qiblah, prayer times, and crescent sighting and calendar,
but also astrology (the effect of celestial changes on earthly events, i.e. marriage,
war, construction, etc.) and cosmology, the structure of the heavens. As to the
characteristics of classical Islamic astronomy, they can be summarized in 3 broad
trends: a) a big effort to improve the observational knowledge/data of celestial
positions and changes, which led to the construction of big observatories and
instruments; b) an attempt to “fix” Ptolemy’s cosmology by modifying the
geometry of the orbits and/or using more accurate parameters for them; c)
conducting advanced discussions on the ‘physics’ or ‘natural philosophy’ of the
heavens and either tying or disconnecting that from the astronomy (orbits and
motions). I summarize all this succinctly and try to extract lessons for the present
and future of Islamic astronomy. I then ask: what topics and methods should the
Islamic astronomy of the 21st century take on? I believe that the qibla problem has
long been solved, even though many mosques around the world are badly
oriented; so perhaps what is needed in this regard is a good communication
effort. I also believe that the problem of crescent sighting determination (criteria)
is largely solved and what remains is to fine-tune and agree on an Islamic
calendar; this requires close engagement with jurists (fuqaha) and officials, as well
as inclusion in educational curricula around the Muslim world. Prayer times are
also largely solved, except for two problems, one minor and one major: a) the
times for Isha and Fajr prayers still suffer some disagreements and controversies
in a number of places, and this needs some effort and attention; b) prayer times
at high latitudes, both where the sun does not set or rise during certain periods of
the year and where it does rise and set but leads to unreasonably long fasting
times (from Fajr to Maghrib). From the golden age, we also learn some lessons
that can be very valuable for the present and future of Islamic astronomy:

Morrison, R G. (2013). Islamic Astronomy. In D C. Lindberg & M H. Shank (Eds.). Cambridge History of Science (vol. 4, 5
pp. 109-138). Cambridge, UK: Cambridge University Press.

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a) building observatories, which can be extremely important for both research
and education; b) engaging in “cosmology”, i.e. topics that go beyond ‘cilm al-falak
al-sharciy’ (astronomy of Islamic practices), and today/tomorrow such topics (will)
include the search for exoplanets and the understanding of ‘cosmology’, the
universe and its history. These two topics allow for and invite an engagement of
astronomical research with theo-philosophical ideas. Finally, it will be important
to bring ‘Islamic astronomy’ closer to and more fully into education, at various
levels.

Introduction: What is Islamic Astronomy?

What is ‘Islamic Astronomy’? Are there religious or cultural or ethnic types of
science, e.g. Christian Biology or Chinese Geology or Hindu Physics?

No, there are ethnically or religiously labeled types of science, as science is and
must be a universal and objective knowledge production activity, where the same
results are obtained by all practitioners regardless of their social or cultural
backgrounds or their personal beliefs.

‘Islamic Astronomy’ is rather unique in existing as a recognized collection of
astronomical activity and production that actually stemmed from and refer to a
cultural, religious or historical milieu. The earliest usage of this expression that I
could find in modern scientific literature is by Rufus6, in 1939, The Influence of
Islamic Astronomy in Europe and the Far East; however, a recent work
(Morrison 2013) gives a good definition for the expression:

In this chapter, “Islamic astronomy” designates the astronomy of Islamic
civilization, the civilization of regions where Islam was the religion of either the
rulers (Muslims were a minority in their own empire at the beginning of Islamic
history) or the majority of the populace (some rulers did not convert to Islam).
The expression “Islamic” thus includes scientists, patrons and students from
diverse religious and ethnic backgrounds and scientific texts in a variety of
languages.

Morrison also briefly explains how ‘Islamic Astronomy’ distinguished itself from
the astronomies that preceded it: a) many of its research problems stemmed
from life activities of Muslim, both religious (prayer times and directions,
occasions such as Ramadan, Eids, and Hajj) and profane (timekeeping for various
activities); b) the observations and the models were required to satisfy a double
consistency, with each other first, and internally (physical consistency of the

6 Rufus, W. C. (1939). The Influence of Islamic Astronomy in Europe and the Far East. Popular Astronomy,
47, 233.

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models) second. Morrison also mentions that astrology was widely practiced by
astronomers during that period; however, many of them were not convinced by
it, either on philosophical principles or on practical grounds, i.e. a lack of
accuracy and predictive power.

Owen Gingerich, in a review article on Islamic Astronomy, also explains the
factors that help it flourish in that golden era:

Two circumstances fostered the growth of astronomy in Islamic lands. One was
geographic proximity to the world of ancient learning, coupled with a tolerance
for scholars of other creeds. In the ninth century most of the Greek scientific
texts were translated into Arabic, including Ptolemy’s Syntaxis, the apex of
ancient astronomy… (Indeed, the Syntaxis is still known primarily by its Arabic
name, Almagest, meaning "the greatest.")

The second impetus came from Islamic religious observances, which presented a
host of problems in mathematical astronomy, mostly related to timekeeping. In
solving these problems, the Islamic scholars went far beyond the Greek
mathematical methods. These developments, notably in the field of trigonometry,
provided the essential tools for the creation of Western Renaissance astronomy.

By the ninth century the six modern trigonometric functions--sine and cosine,
tangent and cotangent, secant and cosecant--had been identified, whereas
Ptolemy knew only a single chord function. Of the six, five seem to be essentially
Arabic in origin; only the sine function was introduced into Islam from India.

Thus, before we succinctly review the main contributions of this historical
(medieval) Islamic astronomy, we should draw up and underscore its main
characteristics.

First and foremost, one must not believe that Islamic astronomy should
necessarily be solely concerned with religious applications of astronomy, i.e.
prayer times, crescent visibility and Islamic calendar issues, as seems to be the
general understanding today. As mentioned above, and as we shall see in the brief
review that will follow, Muslim astronomers spent more time constructing
models of planetary orbits, the “inner cosmology” (anything closer than the stars)
of their time, than producing prayer tables or determining the start and end of
Ramadan.

However, Islamic astronomy, while keeping a strong research program,
modifying Ptolemy’s model and parameters and discussions both geometric and
physical aspects of their cosmology (sizes of planets, distances to earth, ensuring
no intersections), most often showed interest and made their knowledge at the

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service of their communities and rulers, either by producing calendars, qibla
directions for mosques, and prayer tables, or by computing planetary positions
for astrological purposes (wedding dates, war times, construction of important
buildings, etc.). Islamic astronomy of the twenty-first century should take its cues
from that golden era.

A Brief History of Islamic Astronomy

Practical Astronomy and Islamic Fiqh and Kalam

As I have mentioned, one important branch of astronomy during the golden age
of the Islamic civilization was the determination of prayer times, crescent
visibility dates (for Ramadan, Eids and Hajj), qibla directions (as accurately as
possible, for mosque construction in particular), calendars (for civil and religious
purposes, i.e. payment of salaries, loans, etc.), and general geography (directions,
distances, etc.) and timekeeping (hours and days for work, travel, etc.). Moreover,
and besides this Fiqh (Islamic jurisprudence) connection, astronomy was
sometimes related to Kalam (Islamic theology), exegesis (tafseer, interpretations of
and commentaries on Qur’anic verses), etc.

Indeed, works on the qibla problem spurred the development of spherical
trigonometry and astronomy, even though adoptions and applications in
mosques varied substantially from one region to another and from one era to
another7.

One of the earliest known tables for the five daily prayer times was constructed
by Al-Khwarizmi (780-850 CE), who performed his calculations for Baghdad and
similar latitudes but also showed how to shift the times for other longitudes, by
six-degree increments8.

Al-Khwarizmi also wrote the earliest known work on sundials, which were the
standard way of determining time during the day, explaining how the latitude
affects the line that the gnomon’s shadow traces from hour to hour. And Thabit
ibn Qurra (836-901 CE) showed how a sundial could be constructed to work at
any latitude9.

7 See, for a critical and historical treatment: Dallal, A. (2010). Islam, science, and the challenge of history. Yale
University Press.
8 Morrison 2013, citing Bernard Goldstein, Ibn al-Muthanna’s Commentary on the Astronomical Tables of al-
Khwarizmı (New Haven, Conn.: Yale University Press, 1967); and Otto Neugebauer, The Astronomical Tables of
al-Khwarizmı: Translation with Commentaries of the Latin Version edited by H. Suter (Copenhagen: Munksgaard,
1962).
9Morrison 2013, citing Fuat Sezgin, Geschichte des arabischen Schritfttums, 13 vols. (Leiden: Brill, 1978), vol. 6, p.
143, and Régis Morelon, “Thabit ibn Qurra and Arabic Astronomy in the Ninth Century,” Arabic Sciences and
Philosophy, 4 (1994), 111–39.

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The function of the muwaqqit (religious timekeeper) appeared during the Mamluk
period (1250-1517) as ‘ilm al-miqat (the science of timekeeping) became an
accepted branch of astronomy. Perhaps the most famous astronomers to hold
the muwaqqit function was Ibn al-Shatir (1304-1375), who worked at the Umayyad
Mosque of Damascus and built a sundial there for the above purposes.

The problem of the visibility of the lunar crescent is very old, with the first
systematic studies dating back to the early Islamic era (which began in the eighth
century). Earliest tables of new crescents were based on Indian astronomy 10.
Gradually, however, Muslim astronomers developed several criteria for the
observability of the new crescent, in order to allow the precise prediction of the
start of the new month (Guessoum et al. 1997). Based on a purely geometrical
approach, the criteria that were devised remained imprecise, mainly because they
did not take into account the conditions of observation, which prove particularly
important.

Research, both theoretical and observational, was undertaken during that period;
computational methods were thus devised, and several first-visibility criteria for
the new crescent were proposed. Many of the great, famous astronomers of that
time worked seriously on this problem, among them: Ibn Tāriq (8th century), al-
Khwārizmī (d. 863), al-Battānī (859-929), Ibn Yūnus (11th century), al-Tabarī (11th
century), al-Tūsī (1207-1274). In the following paragraphs we wish to present a
brief review of the criteria they developed; for a more thorough and detailed
discussion, we refer the reader to the literature (Bruin 1977, Hogendijk 1988,
Kennedy and Janjanian 1965, King 1988, and others).

Astronomy became more widely important and influential in the later centuries
of the Islamic era, that is from the 13th century onward. The study of astronomy
became common in Mamluk madrasas11. Many astronomers, including Ibn al-
Shatir and Shırazı (Qutb al-Din, 1236-1311), served in a religious capacity. The
famous Al-Tusı (see later) was an eminent Shiite theologian, and Sadr al-Sharıca
(d. 1347) wrote a three-part encyclopedia on astronomy, Kalam, and Fiqh12.

A remarkable combination of education and observational astronomy existed in
the great Samarkand observatory, which was built in the 1420’s under the
leadership of the Timurid sultan and astronomer Ulugh Begh (1394-1449).

10 E. S. Kennedy and Mardiros Janjanian, “The Crescent Visibility Table in Al-Khwarizmı’s Zıj,” Centaurus,
20 (1965–1967), 73–8
11 Morrison 2013, citing Franc¸ois Charette, “The Locales of Islamic Astronomical Instrumentation,” History
of Science, 44 (2006), 123–38
12 See Dallal, A. S. (Ed.). (1995). An Islamic Response to Greek Astronomy (Kitab Tadil Hay’at Al-Aflak of Sadr al-
Sharı‘a (Vol. 23). BRILL, and Dallal, A. (2010). Islam, science, and the challenge of history. Yale University Press.
pp. 135–38

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Indeed, the institution was not only one of the greatest observatories ever built
(at least until the second half of the 20th century), with one instrument (a
meridian sextant) built into the ground, with a radius of over 40 meters, but also
a great place of learning, a madrasa, where astronomy was purposefully and
carefully built into the curriculum13. One of its most illustrious astronomers (see
later) was ‘Ala’ al-Dın al-Qushji (1403-1474). He wrote significant works on
Kalam in connection to his astronomical research, while insisting that astronomy
must remain independent of philosophical principles14.

Astrology

Astrology (the idea that celestial objects and their motions affect lives and events
here on Earth) was rather widely practiced in the Islamic culture15, having been
inherited from earlier cultures, starting with the Babylonians and reaching the
Greeks as well as other peoples. Perhaps because astrology lacked accuracy and
precision in its “predictions”, it was not considered as ‘ilm ghayb (knowledge of
the “unknown”) and thus not obviously haram (unlawful). Thus, discussions
around astrology revolved around its philosophical/scientific bases and its
accuracy or lack thereof.

For instance, no less an illustrious figure than Abu Rayhan al-Biruni (973-1048),
covered the application of astronomy to astrology in his Kitab al-Tafhım fı ‘ilm al-
tanjım (The book of exposition of the science of stars); however, he expressed his
lack of conviction in astrology due to its weak theoretical bases as well as lack of
predictive accuracy.

Astrology, ‘ilm al-ahkam (the science of rules or judgments), was in demand by
both the rulers, who wanted to know the most propitious times for marrying,
constructing palaces and important buildings, or waging wars, and laymen (at
least those who could afford such orders, which the astronomers obviously
charged good money for) for important daily affairs (commerce, weddings, etc.).
Most importantly, as far as we are concerned, astrology needed astronomical
knowledge and data, i.e. observations and calculations. Thus astronomy, ‘ilm al-
hay’a (the science of the configuration [of the stars]), became intertwined with
astrology, so that ‘ilm al-nujum (the science of stars) could mean either of those
two “sciences”. Likewise, Ibn Sina (980-1037) criticized astrology for its inability
to produce reliable results.

13 See Morrison, page 137, and references therein.
14 Ragep, F. J. (2001). Freeing Astronomy from Philosophy: An Aspect of Islamic Influence
on Science. Osiris, 16, 49-71.
15 T. Fahd, Nujum (Ahkam al-), in Encyclopaedia of Islam, new edition, ed. P. J. Bearman et
al. (Leiden: Brill, 1997), vol. 8, pp. 105–8.

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Finally, we may note that astrology continued into the Ottoman era, as another
illustrious astronomer, Taqi al-Dın Ibn Ma‘ruf (1526-1585), the founder of the
Istanbul observatory, astrologically predicted military success for the Ottomans
against the Safavids based on the comet of 157716.

Observational Astronomy

As I have mentioned, one of the main and greatest features of Islamic astronomy
was the extensive effort and care to produce accurate observational data, which
meant the development of large and precise instruments as well as observatories.

Precise observations were performed for the Sun; Al-Battani (858-929), in
particular, not only measured the angular diameter of the sun but noted its
variation, which had been predicted by Ptolemy but not measured. This particular
feature was important in that it implied the possibility of annular eclipses17.

Another illustrious Islamic astronomer, ‘Abd al-Rahman al-Sufı (903-986),
performed a precise measurement of the obliquity of the ecliptic using an
instrument that was probably 2.5 meters in diameter18.

Al-Biruni conducted numerous observations of eclipses and equinox times, some
of which were later used as part of a study of Earth's past rotation19. One historic,
collaborative observation he conducted with Abu al-Wafa’ al-Buzjanı (940-998),
himself a key figure in the development of spherical trigonometry, when they
observed the lunar eclipse of 997 (Al-Biruni in Khwarizm and Al-Buzjanı in
Baghdad) to try to determine the difference in longitude between the two
locations, (Al-Biruni had done for other places, e.g. Jurjan and Ghaznah)20.

Al-Biruni is also famous for having reported that some Indian astronomers had
argued for heliocentric system of the world (as had Aristarchus in the third
century BCE), with Earth moving, both around itself and around the Sun, and
that one not try to reject any such hypothesis on philosophical grounds but rather
on observational ones21.

Finally, one important observational problem that the Maragha Observatory
astronomers were unable to resolve fully was that of planetary sizes and
distances. For example, while Ibn Sina had reported that Venus was observed

16 Sayili, A. (1981). The observatory in Islam. New York: Arno Press. pp. 290-291.
17 See Morrison, page 120, and references therein.
18 Sayılı, The Observatory in Islam, pp. 105–6.
19 Ibid
20 Stephenson, F. R. 2009. Historical Eclipses and Earth’s Rotation. Cambridge: Cambridge University Press.
21 Abu al-Rayhan al-Bırunı, al-Qanun al-Masudı, 3 vols. Hyderabad: Da’irat al-maarif al-‘uthmaniyya, 1954–
1956. pp. 54-5

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transiting (i.e. passing in front of) the Sun, Al- Urdı’s concluded from his own
extensive research that Venus must be beyond the Sun22.

Cosmology

In the past fifty years or so, important new knowledge has been added to the
history of medieval and renaissance astronomy leading to interesting and rather
hot debates about the role and impact of Islamic astronomy in the Copernican
revolution. Before we get to that, we need to review the cosmological paradigm
that prevailed in Islamic astronomy, namely the geocentric Ptolemaic system,
which can be summarized in the following two main ideas: a) planets (this then
included the Sun and the Moon and the five planets that are visible to the naked
eye) orbit the Earth in orbits that consist of small circles (epicycles) that rotate
around big circles (deferent); b) additional, “secondary” components such as the
equant, that is a point which is opposite to the Earth w.r.t. to the center of the
deferent and about which the speeds of the planets would be uniform (see Figure
1).

Planet

Equan Earth
t

Center of
Deferent

Figure 1 – A Ptolemaic model of a planetary orbit, where in addition to epicycles
around a deferent, an “equant” has been introduced: the Earth is shifted away
from the center of the deferent, and the point symmetric to Earth w.r.t. the
center is the equant; the planet is then constrained to move uniformly about the
equant.

22 Morrison, page 134, citing Bernard Goldstein, “Theory and Observation in Medieval Astronomy,” Isis, 63
(1972), 39–47.

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It was not unusual or rare for Muslim astronomers to formulate “doubts”
(shukuk) or critiques regarding this Ptolemaic system (Ibn al-Haytham was one of
the first to voice such doubts/critiques), but these were often (though not
always) made on philosophical rather than observational bases, and they never
called into question the geocentric nature of the model. The equant was
particularly bothersome to the Muslim astronomers, who often preferred a
system with the Earth exactly at the center, and with perfect circles and uniform
motions. Ibn Rushd (1126-1182), the great Andalusian philosopher, strongly
objected to the whole system on precisely such grounds and declared it to thus be
no more than a mathematical construct that is “contrary to nature.” Another
Andalusian astronomer, Al-Bitruji (Nur al-Din Ibn Ishaq, d. ca. 1204), whose
different order of the planets (placing Venus above the Sun) was cited by
Copernicus, went so far as to construct a strictly geocentric model, which turned
out to be disastrous 23 . Nasir al-Din Al-Tusi (1201–1274), another great
astronomer, philosopher, and scientist (for whom Ulugh Khan built the famous
Maragha observatory), also got rid of the equant in his model; he did so by
adding two small epicycles to each planet’s orbit, the famous “Tusi couple”. Tusi
thus launched an influential new “school” of Astronomy, which included
Mu’ayyad al-Din al-‘Urdi (1200-1266) and Qutb al-Din al-Shirazi (1236–1311),
followed by Ibn al-Shatir24, substantially modified Ptolemy’s system, adopting
completely concentric arrangements.

Secondly, more careful examinations of Copernicus’s two works, the
Commentariolus and De Revolutionibus, showed him to have adopted, sometimes
literally, the mathematical and geometrical bases and conventions of the (Muslim)
‘Maragha School’ of astronomy (al-Tusi, al-‘Urdi, and others), which had
seriously modified the Ptolemaic prescriptions for planetary orbits. This opened
the debate among scholars around the question of the extent to which
Copernicus had benefited from the “transmission” of those models and critiques
of Ptolemy. The question has remained open, mainly due to the absence of
sufficient historical data, and scholars are largely divided over how far the Muslim
astronomers had gone in their critiques of Ptolemy, particularly the extent to

23 Morrison writes: “[Al-Bitrujı’s] model predicted that the sun would stray as much as 1.5◦ from its observed
path through the zodiac, a significant error. With the upper planets, the divergences in latitude were much
greater.” Al-Bitrujı, On the Principles of Astronomy, ed., trans., and intro. Bernard R. Goldstein, 2 vols. (New
Haven, Conn.: Yale University Press, 1971).
24 Gingerich quotes Ibn al-Shatir on how he came to construct his model: “I therefore asked Almighty God
to give me inspiration and help me to invent models that would achieve what was required, and God--may
He be praised and exalted—did enable me to devise universal models for the planetary motions in longitude
and latitude and all other observable features of their motions, models that were free from the doubts
surrounding previous ones.”

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