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The Impact of Light Pollution on Islamic New Moon (hilal) Observation

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Muslims has differentiated between new moon and Islamic new moon (hilal). The determination of first day of months based on visibility of Islamic new moon (hilal) i.e. sightings of the first sliver of the waxing moon marking the start of each month. One major issue that has affected hilal visibility for many years is misdirected, excessive and obtrusive artificial light. The objective of this research is to study the impact of light pollution on the visibility of hilal. The data were taken using Sky Quality Meter (SQM) which records the visual magnitudes per square arcsecond (mpsas) to measure sky limiting magnitude. Result showed that reading between 16-22 mpsas, the chances to witness hilal is high. Any lower than 16mpsas, the hilal is not visible. The main result of this research is to find out a vital parameter of hilal observations which leads to propose a new criterion i.e. sky limiting magnitude.
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N.N.M. Shariff et al. /International Journal of Sustainable Lighting 19 (2017) 10-14 https://doi.org/10.26607/ijsl.v19i1.61
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The Impact of Light Pollution on Islamic New Moon (hilal)
Observation
Nur Nafhatun Md Shariff1,3,*, Zety Sharizat Hamidi2,3, Muhamad Syazwan Faid1
1 1Academy of Contemporary Islamic Studies, Universiti Teknologi MARA, Shah Alam,
40450, Malaysia
2Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, 40450, Malaysia
3Institute of Science, Universiti Teknologi MARA, 40450, Shah Alam, Selangor,
Malaysia
Received 05 December 2016, Accepted 08 February 2017
Abstract
Muslims has differentiated between new moon and Islamic new moon (hilal). The determination of first day of
months based on visibility of Islamic new moon (hilal) i.e. sightings of the first sliver of the waxing moon marking
the start of each month. One major issue that has affected hilal visibility for many years is misdirected, excessive
and obtrusive artificial light. The objective of this research is to study the impact of light pollution on the visibility
of hilal. The data were taken using Sky Quality Meter (SQM) which records the visual magnitudes per square
arcsecond (mpsas) to measure sky limiting magnitude. Result showed that reading between 16-22 mpsas, the
chances to witness hilal is high. Any lower than 16mpsas, the hilal is not visible. The main result of this research
is to find out a vital parameter of hilal observations which leads to propose a new criterion i.e. sky limiting
magnitude.
Keywords: light pollution, Islamic New Moon, hilal, night sky brightness, Sky Quality Meter (SQM).
1. Introduction
Due to religious obligation, Muslims has differentiated between new moon and Islamic new moon (hilal). This
is based on Quranic verse: “They ask you about the crescent moons; say they are a means to measure your specific
times (mawaqit) and are also for the commencement of the hajj” (2: 189). Islamic calendar is regulated by the first
appearance of the lunar crescent. Therefore, the observation to determine the month began with the first sighting
of the crescent moon - sliver of the waxing moon on the day 29th [1]. If the crescent moon is seen at western
sky after sunset, the new month begins on the next day [2, 3]. If the crescent moon is not seen due to the sky was
cloudy etc., the calendar would be assuming a fixed number of days for the month just completed [4] either 29 or
30 days and never 31 days.
The thin crescent (Ar. hilal) can possibly be seen in hours pass after the conjunction in the first phase of the
Moon which term as “moon’s age” [5, 6]. The word hilal means the first light of the Moon when people actually
see the crescent at the outset of a month [7]. The conjunction occurs when moon and sun have the same elliptical
longitude or in other word is in conjunction [8]. Conjunction is only an apparent phenomenon due to the
* Shariff NNM, Tel.: +60-35544-8262.
E-mail address: nur.nafhatun.ms@gmail.com
N.N.M. Shariff et al. /International Journal of Sustainable Lighting 19 (2017) 10-14 https://doi.org/10.26607/ijsl.v19i1.61
11
perspective. At this point, we cannot see the Moon because we cannot see the reflected sunlight on the Moon’s
surface Fig. 1.
Fig. 1. Phases of the Moon (Credit to Google Image)
Astronomers such as al-Khwarizmi, knew that the determination of the possibility of sighting on a given day
was a complicated mathematical problem. Thus it is vital to understand the positions of the Sun and the Moon and
the mathematical investigation of the positions of the both celestial bodies relative to each other and to the local
horizon [4]. In short, certain criteria required to assure crescent visibility on most occasions can be determined by
observation. By combining several criteria, there are three basic methodology that in determining the month: 1)
physical sighting or naked eye observation (rukyah); 2) astronomical/calculation basis (hisab falak); and 3)
physico-astronomical basis (imkan al-rukyah which lit. possible of visibility by observation) [9].
Before 1970, Malaysia adopted rukyah method in determining the beginning of month [10]. Malaysia then
opted to choose imkan al-rukyah method in 1992 until present time [11]. Basically, imkan al-rukyah has three (3)
criteria: 1) > 2o of Moon’s altitude; AND 2) > 3o of Moon-Sun elongation; OR 3) minimum of eight (8) hours of
Moon’s age Figure 2.
Fig. 2. Imkan al-rukyah method
It is important to note that, it is possible to calculate when this thin crescent will theoretically be visible, but
many Muslims will only accept visual confirmation [12]. Figure 3 shows the elusive thin crescent of Sha’ban
1431H was visible with 1) Moon’s altitude: 1o41’48”; 2) Elongation: 8.5o; and 3) Moon’s age: 16:09 hours.
Although the Moon’s altitude did not meet the imkan al-rukyah criteria but Moon’s age surpass the minimum of
eight (8) hours, thus, the next day was considered new month.
N.N.M. Shariff et al. /International Journal of Sustainable Lighting 19 (2017) 10-14 https://doi.org/10.26607/ijsl.v19i1.61
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Fig. 3. The elusive thin crescent of Sha’ban 1431H
Since there was no study on sky limiting magnitude at site in Table 1, we hypothesized that light pollution
really has impact on the crescent observation which is based on hilal observation report from 1972-2015 by JAKIM
(Malaysia Department of Islamic Development), before 1990, the hilal was more frequently seen in 29th day.
After 1990, the hilal was frequently seen in 30th day Table 1 [13].
Table 1. Part of JAKIM observation report
No
Date*
Date** (H)
Altitude
Elongation
Moon’s Age
Site
1
6-Nov-72
29 Ramadan 1392
1.227
5.853
9.73
Telok Kemang
2
26-Oct-73
29 Ramadan 1393
0.564
5.302
7.96
Telok Kemang
3
16-Nov-74
29 Ramadan 1394
26.402
28.313
58.08
Telok Kemang
4
24-Sep-76
29 Ramadan 1394
5.298
8.337
15.64
Telok Kemang
5
16-Apr-80
1 Jak 1400
13.649
18.253
31.78
Telok Kemang
6
15-May-80
29 Jamadilawal 1400
11.882
13.172
24.36
Pulau Sayak
7
15-May-80
29 Jamadilawal 1400
11.908
13.002
24.06
Pontian Kecil
8
15-May-80
29 Jamadilawal 1400
12.039
13.066
24.2
Telok Kemang
9
15-May-80
29 Jamadilawal 1400
11.908
13.002
23.15
Johor Bahru
10
9-Nov-80
1 Muh 1401
11.896
17.456
38.57
Telok Kemang
11
1-Aug-81
29 Ram 1401
14.72
15.929
31.57
Telok Kemang
12
11-Jul-83
29 Ram 1403
12.093
12.983
23.13
Telok Kemang
13
29-Jun-84
29 Ram 1404
3.051
4.498
8.38
Telok Kemang
14
6-May-89
29 Ramadan 1409
7.412
13.863
23.91
Pantai Acheh
15
6-May-89
29 Ramadan 1409
2.777
13.958
24.09
Bkt. Sg. Besi
16
6-May-89
29 Ramadan 1409
6.84
13.803
23.74
Telok Kemang
17
6-May-89
29 Ramadan 1409
6.851
13.862
23.89
Pasir Panjang
18
6-May-89
29 Ramadan 1409
9.647
13.696
23.58
Pulau Perhentian
19
6-May-89
29 Ramadan 1409
2.398
13.492
23.26
W.P. Labuan
* Gregorian calendar ** Islamic calendar
Recent study showed Telok Kemang light pollution level has getting worsen due to artificial light [14]. One
major issue that has affected hilal visibility for many years is misdirected, excessive and obtrusive artificial light.
The unwanted light is what we called as light pollution and it is unavoidable as well. Nowadays, people are
concerned about the environment but find other issues more important. Due to that, people are not aware enough
of light pollution although light pollution does have impacts. Light pollution may appear to cause no direct harm
N.N.M. Shariff et al. /International Journal of Sustainable Lighting 19 (2017) 10-14 https://doi.org/10.26607/ijsl.v19i1.61
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to the environment like other forms of pollution but it has a tremendous impact towards human health, nocturnal
creatures and not to mention night sky heritage which is very important for optical astronomy. Moreover, light
pollution is a form of waste (electric energy) that eventually contributes to the environmental degradation [15].
From astronomical perspective, limiting magnitude is the faintest apparent magnitude of a celestial body that
is detectable or detected by a given instrument. Therefore, the objective of this research is to measure the value of
sky limiting magnitude during the crescent observation as we believe sky limiting magnitude has influence over
the visibility of hilal. The visibility of new moon is a function primarily of the angle between the moon, observer,
and sun (which affects the brightness of the crescent) and the apparent altitude of the moon above the horizon and
of the sun below the horizon (which affects the background brightness against which the moon is to be observed).
2. Methodology
To conduct this research, we choose west-facing sites because the hilal sets at west. The sites are: 1) Telok
Kemang, Malaysia; 2) Kuala Lumpur, Malaysia; and 3) Coonabarabran, Australia. The data were taken using Sky
Quality Meter (SQM; to be specific SQM-LU) which records the visual magnitudes per square arcsecond (mpsas)
to measure sky limiting magnitude. The SQM was pointed to horizon in order to get magnitude value of sky with
hilal in the measurement cone, we believe the albedo of crescent is very minuscule Fig. 4. Measurements of the
limiting magnitude were made at least one hour before and after the Moon set on dates spread over a period of six
months.
Fig. 4. Data taking using Sky Quality Meter (SQM) during the observation at twilight
3. Result and Discussion
Table 2 below is the preliminary results of this research which is the sky limiting magnitude threshold for the
hilal to be witnessed. The given readings imply that reading within that range, there is high possibility to witness
the hilal because the hilal quickly set depending on Moon’s altitude (normally very low) during observation. On
the other hand, reading with less than 16 mpsas, the hilal was not visible during the observation.
Table 2. Limiting magnitude threshold
NO.
SITE
READING (in mpsas)
1.
Telok Kemang, Malaysia
16-19
2.
Kuala Lumpur, Malaysia
16-18
3.
Coonabarabran, Australia
16-22
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4. Conclusion
Although it is a long way to go, based on the result, we hope that sky limiting magnitude can be a new criterion
in determining new month in Islamic calendar. This research helps us to understand the phenomenon better about
the threshold of sky limiting magnitude for hilal.
Acknowledgment
The authors wish to thank the referee for comments and suggestions to improve the paper. This work was
partially supported by RAGS/1/2014/SSI03UITM//2 (MOE) and Universiti Teknologi MARA. Special thanks to
JAKIM for generously providing the data.
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... While it has been accepted that the nature of sky brightness during twilight is mainly factored by the sun depression below the horizon, coupled with major variables of ozone composition and aerosol concentration, the research on twilight has never considered the effect of light pollution on its lumination and colour profile. The anthropogenic by-product of the human population, light pollution alters the profile night sky [14] in the form of artificial lighting [14], disrupting the natural limiting contrast of celestial object visibility [15]. This makes the light pollution monitoring is a continuous concern for astronomers throughout years considering its factor on the both optical and radio observation [16], and it has been made mandatory to determine the quality of the observation site [17]. ...
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Pengenalan Ilmu Falak, Dewan Bahasa dan Pustaka
  • B Zainal
Zainal, B. (2002). Pengenalan Ilmu Falak, Dewan Bahasa dan Pustaka, Kuala Lumpur.
A simplified crescent visibility criterion
  • A Özlem
Özlem, A. (2014). A simplified crescent visibility criterion. from http://www.icoproject.org/pdf/ ozlem_2014.pdf
Cesarean moon births: calculations, moon sighting, and the prophetic way
  • H Yusuf
Yusuf, H. (2008). Cesarean moon births: calculations, moon sighting, and the prophetic way, Zaytuna Institute,
Sistem kalendar Islam dari perspektif astronomi
  • M Ilyas
Ilyas, M. (1997). Sistem kalendar Islam dari perspektif astronomi. Dewan Bahasa dan Pustaka.