The Impact of Light Pollution on Is= lamic New Moon (hilal) Observation
Nur Na= fhatun Md Shariff1,3,*, Zety Sharizat Hamidi2,3, Muhamad Syazwan Faid1
2Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, 40450, Malaysia<= /span>
3Institute of Science, Universiti Teknologi MARA, 40450, Shah Alam, Selang= or,
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 s=
tart
of each month. One major issue that has affected hilal visibility for many
years is misdirected, excessive and obtrusive artificial light. The objecti=
ve
of this research is to study the impact of light pollution on the visibilit=
y 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, hil=
al,
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 mean=
s 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 t=
he
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 beg=
ins
on the next day [2,
3].
If the crescent moon is not seen due to the sky was cloudy etc., the calend=
ar
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 whi=
ch
term as ¡°moon¡¯s age¡± [5,
6].
The word hilal means the first light of the Moon when people actually see t=
he
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 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 Im=
age)
Astronomers such as al-Khwarizmi, knew that=
the
determination of the possibility of sighting on a given day was a complicat=
ed
mathematical problem. Thus it is vital to understand the positions of the S=
un
and the Moon and the mathematical investigation of the positions of the both
celestial bodies relative to each other and to the local horizon ADDIN EN.CITE
<EndNote><Cite><Author>King</Author><Year>201=
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t;<ref-type
name=3D"Book">6</ref-type><contributors><author=
s><author>David
A.
King</author></authors></contributors><titles><t=
itle>Astronomy
in the Service of
Islam</title></titles><dates><year>2014</year>=
;</dates><pub-location>New
York</pub-location><publisher>Springer</publisher><url=
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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 bas=
is
(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 possibl=
e 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.
Fig. 3. The elusive thin crescent of Sha¡¯ban 1=
431H
Since there was no study on sky limiting
magnitude at site in Table 1, we hypothesized that light pollution really h=
as
impact on the crescent observation which is based on hilal observation repo=
rt
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 J=
AKIM
observation report
|
No |
Date* =
|
Date** (H) |
Altitu=
de |
Elonga=
tion |
Moon¡¯=
s Age |
Relati=
ve
Azimuth |
Site |
|
1 |
6-Nov-72 |
29 Ram=
adan
1392 |
1.227 |
5.853 |
9.73 |
5.595 |
Telok Kemang |
|
2 |
26-Oct-73 |
29 Ram=
adan
1393 |
0.564 |
5.302 |
7.96 |
5.209 |
Telok Kemang |
|
3 |
16-Nov-74 |
29 Ram=
adan
1394 |
26.402 |
28.313 |
58.08 |
7.762 |
Telok Kemang |
|
4 |
24-Sep-76 |
29 Ram=
adan
1394 |
5.298 |
8.337 |
15.64 |
5.757 |
Telok Kemang |
|
5 |
16-Apr-80 |
1 Jak =
1400 |
13.649 |
18.253 |
31.78 |
0.893 |
Telok Kemang |
|
6 |
15-May-80 |
29
Jamadilawal 1400 |
11.882 |
13.172 |
24.36 |
3.14 |
Pulau Sayak |
|
7 |
15-May-80 |
29
Jamadilawal 1400 |
11.908 |
13.002 |
24.06 |
2.094 |
Pontian Kecil |
|
8 |
15-May-80 |
29
Jamadilawal 1400 |
12.039 |
13.066 |
24.2 |
2.319 |
Telok Kemang |
|
9 |
15-May-80 |
29
Jamadilawal 1400 |
11.908 |
13.002 |
23.15 |
2.094 |
Johor Bahru |
|
10 |
9-Nov-80 |
1 Muh =
1401 |
11.896 |
17.456 |
38.57 |
0.697 |
Telok Kemang |
|
11 |
1-Aug-81 |
29 Ram
1401 |
14.72 |
15.929 |
31.57 |
3.194 |
Telok Kemang |
|
12 |
11-Jul-83 |
29 Ram
1403 |
12.093 |
12.983 |
23.13 |
0.59 |
Telok Kemang |
|
13 |
29-Jun-84 |
29 Ram
1404 |
3.051 |
4.498 |
8.38 |
2.555 |
Telok Kemang |
|
14 |
6-May-89 |
29 Ram=
adan
1409 |
7.412 |
13.863 |
23.91 |
7.369 |
Pantai Acheh |
|
15 |
6-May-89 |
29 Ram=
adan
1409 |
2.777 |
13.958 |
24.09 |
7.58 |
Bkt. Sg. Besi |
|
16 |
6-May-89 |
29 Ram=
adan
1409 |
6.84 |
13.803 |
23.74 |
8.018 |
Telok Kemang |
|
17 |
6-May-89 |
29 Ram=
adan
1409 |
6.851 |
13.862 |
23.89 |
7.572 |
Pasir Panjang |
|
18 |
6-May-89 |
29 Ram=
adan
1409 |
9.647 |
13.696 |
23.58 |
7.439 |
Pulau Perhentian |
|
19 |
6-May-89 |
29 Ram=
adan
1409 |
2.398 |
13.492 |
23.26 |
6.922 |
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 alth=
ough
light pollution does have impacts. Light pollution may appear to cause no
direct harm to the environment like other forms of pollution but it has a
tremendous impact towards human health, nocturnal creatures and not to ment=
ion
night sky heritage – which is very important for optical astronomy. M=
oreover,
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 t=
his
research is to measure the value of sky limiting magnitude during the cresc=
ent
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-fa=
cing
sites – because the hilal sets at west. The sites are: 1) Telok Keman=
g,
Malaysia; 2) Kuala Lumpur, Malaysia; and 3) Coonabarabran, Australia. The d=
ata
were taken using Sky Quality Meter (SQM; to be specific SQM-LU) which recor=
ds
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 twil=
ight
3.
Result and Discussion
Table 2 below is the preliminary results of
this research which is the sky limiting magnitude threshold for the hilal t=
o be
witnessed. The given readings imply that reading within that range, there is
high possibility to witness the hilal because the hilal quickly set dependi=
ng
on Moon¡¯s altitude (normally very low) during observation. On the other ha=
nd,
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 |
4.
Conclusion
Although it is a long way to go, based on t=
he
result, we hope that sky limiting magnitude can be a new criterion in
determining new month in Islamic calendar. This research helps us to unders=
tand
the phenomenon better about the threshold of sky limiting magnitude for hil=
al.
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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