For those just beginning their stargazing journey, the sky’s most elusive guest is not just a blazing star or a distant nebula—it’s the new moon. Its presence reveals some of the most profound moments in the celestial calendar, particularly in Islamic tradition, where its sighting signals spiritual renewal and the start of holy months.

Why Is the New Moon So Hard to See?

The new moon phase occurs when the Moon is positioned directly between the Earth and the Sun. Here’s why it’s nearly invisible:

• Sunlit Side Faces Away: The side lit by the Sun faces away from Earth, leaving us looking at the Moon’s dark hemisphere.
• Too Close to the Sun: The Moon sets with the Sun, often lost in the Sun’s overwhelming glare and low on the horizon during twilight.
• Slender Crescent: Even a day after the new phase, the Moon appears as a razor-thin crescent—dim, low, and short-sightability in the sky.

Spotting this faint curve requires excellent timing, ideal atmospheric conditions, and a clear western horizon. Where in Brunei Darussalam, it is mostly overcast and heavy presence of clouds which may hindered our visual sight to spot the crescent.

The Significance in Islam: When Lunar Cycle Syncs the Calendar

In the Islamic lunar calendar, each month begins with the visual sighting or Rukyah of the new crescent moon—known as hilal. This sighting isn’t just an astronomical event; it’s deeply spiritual and communal.

The process of sighting the crescent moon is a deeply rooted tradition, referenced in Islamic jurisprudence and considered obligation or Fardhu Kifayah. Rukyahtul hilal is essential to track our calendar, because it is connected to two of the pillars of Islam: fasting and Hajj. These were emphasized by the hadith:

1) “When you see the crescent moon fast, and when you see the crescent moon break the fast” (Sahih Muslim, Hadith: 1081)
2) “Fast by its sighting and stop fasting by its sighting and if it is hidden from you, then complete the number of Syaaban as thirty” (Sahih Bukhari, Hadith: 1909 and Sahih Muslim, Hadith: 1081)

Key Islamic Moments Guided by the Moon:

• Ramadan: Begins with the sighting of the new moon and ends with Aidilfitri upon the next crescent.
• Hajj & AidilAdha: The lunar month of Zulhijjah guides the Hajj pilgrimage and the timing of eids.
• A Timeless Tradition: Muslim communities around the world look to the skies together, continuing a prophetic practice that blends science, observation, and faith.

Observation Tips for Beginners

These are some tips based on my 20-years personal experience in new moon hunting:

• Moon Age: Aim to observe the crescent 15–30 hours after the new moon phase for better visibility. The smaller the age, the less likely it is to be observable by the naked eye. Optical aids such as a telescope or binocular increase your chances of spotting the young hilal.
• Clear Western Horizon: Choose a high vantage point with no obstructions like buildings or trees.
• Basic Instruments: To pinpoint the Moon in the sky, start with a compass to determine its azimuth—or horizontal direction. Then, use a clinometer to gauge the altitude angle above the horizon. For an even smoother new moon hunt, a pair of rangefinder binoculars equipped with a built-in compass and vertical reticle markings can make tracking more precise and efficient.
• Know where to look: Use skymap application such as here to get the altitude and azimuth of the Moon based on your location and date.
• Twilight Timing: Look just after sunset, when the sky darkens and the crescent may briefly glow usually 15 minutes after sundown.
• Use Binoculars First: Spot it through binoculars, then try with the naked eye for confirmation.
• Clouded skies don’t rule out a crescent: A “cloud break” during moon sighting provides a brief clearing in an otherwise overcast sky that allows a glimpse of the hilal.

For new moon hunters in Brunei Darussalam, you can use this chart to guide you when to look up for hilal this year 2025/1447H. For other years 2000-2099, please visit First Visibility of Lunar Crescent (Hilal) and Prediction

Remember to share your moon hunting photos and observation result either positive or negative to #BruneiAstronomy via social media. See how many youngest moons you can spot this year.

Clear sky and happy new moon hunting!

The infographic shows the position of the Moon crescent relative to the Sun’s position about the Western horizon at local sunset, and its predicted visibility based on New Criterion for Lunar Crescent (2005) by Mohammad SH. Odeh. Also presented on the graph are the minimum lines of different criterion to start the new Hijrah month adopted by different country/organization.

Sighting the new crescent on April 01, 2022, is shown in the chart for selected cities. In summary, the Moon is below the Danjon’s Limit and not sufficiently illuminated in order to be seen as a crescent from many region globally. The moon crescent may be seen with difficulty in Hawaii and westernmost part of the world.

These are pre-calculated data, the actual start of the fasting month of Ramadan should be referred to your country’s official authority.

Wallahu’alam bisshawab ( والله أعلمُ بالـصـواب )

(Original visibility chart concept & credit: Mutoha Arkanuddin, Yogyakarta)

Based on the data, the 23-hour old moon is thin and the first light Rabiulawal hilal will be a visible to the naked eyes from Brunei Darussalam.

Look up for a great sky-watching challenge from your home backyard. Here are some tips for you:

• Use binoculars or a telescope and a compass to assist your observation;
• Be sure to find an unobstructed flat horizon in the direction of sunset;
• Start looking shortly after the sun disappears (20 minutes after sunset), then you’ll only have no more than about 30 minutes before moonset;
• Use your hands to measure the approximate distance (in degrees) the sky using your hands and fingers – see below;
• Crystal clear skies is essential.

Abstract

The first part of this dissertation investigates methods of predicting the first visibility of the lunar crescent: an astronomical problem that has attracted the interest of man since ancient times. Many early nations used lunar calendars, the months of which began on the evening of the first sighting of the lunar crescent after conjunction. In modern times, the resolution of this astronomical problem is of special importance -both for historians who need to determine ancient dates exactly and for Muslims around the world, whose religious calendar is lunar. The interest in this matter over the centuries has resulted in the appearance of a number of solutions by a variety of authors for predicting the first visibility of the lunar crescent.

The purpose of the first part of this dissertation is to assess the accuracy of these prediction models using ancient, mediaeval and modern observational data and to explore possible improvement. The study concludes that the concept of a “zone of uncertainty” must be incorporated into any lunar
visibility criterion; it further applies this conclusion to the widely used modern criterion of true lunar altitude versus azimuthal difference between the sun and moon. The observational data show that developing a “zone of uncertainty” in this particular criterion yields the best results of all.

The second part of the dissertation is an investigation of six problems in historical astronomy. These are: (i) assessing the accuracy of solar eclipse observations made by Jesuit astronomers in China; (ii) assessing the accuracy of lunar eclipse observations made by Jesuit astronomers in China; (iii) dating the solar eclipse of Thales; (iv) determining the modern equivalent of the Babylonian angular units of measurement; (v) dating the eclipses of Thucydides; and (vi) dating the solar eclipse of Plutarch. All papers have been published or are currently in press.

Original download link: First visibility of the lunar crescent and other problems in historical astronomy. – Durham e-Theses

Members of Brunei Darussalam Astronomical Society (PABD) held observation in Tutong District, and the crescent was firstly be seen at 6.31 pm via telescope. The crescent age of over 23 hours was also visible with binocular and naked eyes.

The western horizon was partly cloudy and Jupiter was visible at sunset, the Sun was used for telescope alignment reference point.

The sighting of the new moon is a particular subject in astronomy that has fascinated many observers since prehistory. Evidence of early human civilizations using the moon as a basis to measure time in the form of an actual lunar calendar has been discovered in the ancient plains of Scotland, dating back to 8,000 B.C. Professor Samuel L. Macey of the International Society for the Study of Time in his book, Encyclopedia of Time, says that using the moon to measure the passage of seasons was evident as far back as 28,000-30,000 thousand years. Therefore, the method by which we measure the beginning and the end of the new moon phase is indeed a crucial part of determining the accuracy of any lunar calendar.

Since the Islamic months follow a lunar calendar, the start of each month is marked by the first sighting of the crescent moon. It is important to note however, that the Islamic new moon is actually different to the “astronomical new moon”. We define the astronomical new moon as that point when it is in conjunction with the sun, and thus it is actually too close to the sun and is very dark, for most of the lunar disc is in shadow. This point marks the beginning of measurement for the true age of the moon.

We define the Islamic new moon to be that point where we can first spy a very thin crescent. It is during that evening when we can say that a new Islamic month begins, and that the next day would be considered the first day of the new Islamic month. The spotting of this crescent is not just a sole physical task that is judged by approximations—there are still very specific astronomical considerations that aid in the locating and spotting of this nearly-invisible crescent. As expressed by renowned and respected Arab astronomer Muhammad Odeh, “Based on crescent sightings, we start Ramadan, we start Eid. So these astronomical issues are very important in our community, and our objective is to do important work that benefits our community.”

The oldest criterion we know of hails from the ancient land of Babylon. It states that the crescent is visible to the naked eye if at the moment of observation, the angular separation (angle between the moon and the sun) exceeds 12 degrees. This criterion was adopted through the ages by various peoples for whom the moon was the basis of the calendar, whether for religious or civil purposes. In later centuries, Muslim astronomers, including the great Al-Battani, Al-Farghani, Al-Biruni, and Al-Tusi, approached the problem in similar fashion. They obtained limiting values between 9.5 and 12 degrees.

In more recent times, French astronomer André-Louis Danjon proposed of a limit at which the smallest angular separation (center to center) between Sun and Moon at which a lunar crescent can be seen. This value is about 7° based on the crescent observations available to him in the early 1930’s. This value is now known as the Danjon Limit. Thus we can therefore say, that is near-impossible to detect the thinnest crescent if it’s only a few hours old from the point of astronomical new moon. One has to wait perhaps 24 or even 48 hours, to be totally sure of a sighting. This means that the moon would perhaps have over 25 to 40 degrees angular separation from the sun, assuring a well-enough bright thin crescent.

We at Astronomical Solutions Company have asked several astronomers from around the world, how they go about the manner of observing this moment of thin crescent moon, especially with regards in determining the beginning of Ramadhan.

Pakistani astronomer Talha Moon Zia, who studies at the Institute of Space & Planetary Astrophysics (ISPA), at the University of Karachi utilizes a refractor telescope on a manual alt-az mount with a primary lens of 3.54 inch or 90 mm and a focal length of 910 mm. When using a 25 mm eye piece he has a magnification power of 36 times, which he says is suitable for such sightings. In order to assure the accuracy of his sighting, he uses various planetarium software and star chart apps in a mobile phone to locate the position of moon in the sky roughly 15-20 minutes before sunset. He also uses the position of the sun as a reference point to find position of moon. At the moment the sun sets, he then uses “Sky Safari Pro 5” app to get the moon’s accurate position in the sky, and if there’s is a bright star or a planet next to the moon that day, he uses it as a guide to “hop” to moon.

Filipino astronomer Christopher Go, famous for his Jupiter and Saturn images, suggests that a basic GOTO telescope is enough to aid one in locating the thin crescent moon even when it’s very young, provided it is first aligned properly, and that there is nothing obscuring line of sight with the horizon.

Amateur Astronomer Hazarry Ali Ahmad of the Astronomical Society of Brunei Darussalam explains that young moon is extremely challenging to see with the naked eye as the physical appearance of the crescent is super thin, just with a “hair line” thickness as seen through a telescope. Another challenge is that the illuminated fraction on the moon is exceedingly small and one usually gets blinded by the setting sun if it’s not yet twilight. He says that he utilizes naked eye sighting as well as optical aids (such as telescopes and binoculars), but with evolving technology, new moon observation is also done with the help of photography using cameras and CCD imaging.

Filipino amateur astronomer Abdur Rahman Alindao, a science educator from Islamic Studies, Call, and Guidance School (ISCAG Philippines) lives in a muslim community in Manila, where they have a mosque where he conducts his astronomical observation. He sets up his equipment on the roofdeck or minaret, utilizing either a pair of 10×50 binoculars or a 130mm reflector telescope.

Aside from the accuracy of locating the position of the thin crescent moon, there is of course, the usual threat of uncooperative weather during the evening of spotting, and the angle of the moon from the sun that might place it in a position too close to the horizon, thereby blocked by objects observed there. In Pakistan, Zia states that it’s difficult during summer months when sky is cloudy due to the monsoon season. It also happens when thin crescent appears to be very low near horizon (below 9 degrees at sunset) and either buildings or thick layer of dust obscure his views. During summer months observing conditions becomes awful due to high relative humidity that makes sighting of thin crescent nearly impossible.

Hazzary adds that the climate in Brunei is tropical and humid with heavy rainfall almost all year round. This weather affects the seeing of the crescent—it’s mostly cloudy during the Moon sighting that always hinder the observation, but is continued as there is always a chance for the moon to appear between gaps in the clouds. Thus the use of technology to achieve a successful sighting through the use of electronic telescope mounts are installed with computers that have an automatic GOTO feature to point the instrument to the precise position of the astronomical object in the sky. This has greatly assisted new moon observers to align and track the telescope correctly to the Moon.

There have been exponential development of young moon crescent visibility studies/literature made to improve the prediction of the new moon crescent. Some famous contributors in the related research are B. D. Yallop who proposed the ‘best time’ for the first visibility and Khalid Shaukat who proposed the ‘topocentric altitude’ and ‘width of crescent’ criterion.

Apps include MoonCalc by Dr. Monzur Ahmed and Accurate Times by Mohammad Odeh. These software can generate calculations for Sun and Moon ephemeris based on your location as well as showing the possibility of seeing the moon crescent. There is also online application developed by University UNIZA available for regional purpose to compute the location of the new moon via http://www.falak.unisza.edu.my/calc/.

Oman’s criteria in entering the Hijri months is to observe the crescent (with the naked eye or telescopes) both mathematically and practically. That is, if the possibility of seeing the crescent is proven mathematically, astronomy is used to support the astronomical observation and reports, while in the case of negation (the impossibility), astronomy is taken without the need for practical sighting. Oman has an entrepreneurial step and well established in entering the Hijri month by enhancing the astronomical sector. The Ministry of Endowments and Religious Affairs represented by the Astronomical Affairs Department has a significant role in implementing the astronomical and scientific projects related to astronomical observation generally and moon sighting specifically.

“Many countries enter the year’s months by sighting the moon by vision while some only use astronomical calculations and predictions. This criteria (of moon sighting) is not determined by astronomers but scholars due to its legitimacy,” said Ammar Salim Al Rawahi, Director of Astronomical Affairs at the Ministry of Endowment and Religious Affairs (MERA) in Oman.

Despite all the published notes and research on this subject matter, the best way to understand the difficulties and challenges owing to the precision demanded by observation of the thinnest crescent moon, is to do it yourself. If you consider yourself to be more than just an average observer, taking up the challenge to do thin crescent observing is a very interesting and worthy pursuit. As the holy month of Ramadhan approaches, now is the best time to consider investing in a good telescope to undertake this intriguing challenge.

Sources

• Times of Oman (2016) Oman uses scientific way for moon sighting. Times of Oman, [online]. [Accessed 6 May 2018]. http://timesofoman.com/article/93399/Oman/Government/Oman-uses-scientific-way-for-moon-sightingdisqussion-0disqussion-0disqussion-0disqussion-0
• Article on the International Astronomy Centre HQ in Al Bateen, Abu Dhabi https://www.thenational.ae/uae/inside-the-uae-s-astronomical-centre-which-helps-determines-islamic-public-holidays-1.630340
• Answers to questions for astronomers sent via email

Note: Prediction method by Mohammad SH. Odeh (New Criterion For Lunar Crescent Visibility, 2005) employed new criterion visibility of the lunar crescent, V. This is only a computational analysis data. The result/declaration of the sighting/beginning of hijrah month should be referenced to official media by the Government.

It’s rare and very challenging to see a moon within 24 hours of new moon. Our PABD include monthly hilal observation to spot the youngest possible moons with digital camera, optical aid, or with the eye alone.

Prediction method by Mohammad SH. Odeh (New Criterion For Lunar Crescent Visibility, 2005) employed visibility of the lunar crescent by this new criterion, V= ARCV−(−0.1018W3 +0.7319W2 −6.3226W +7.1651) where: ARCV: Airless and topocentric arc of vision in degrees. W: Topocentric crescent width in arc minutes ;
V > 5.65 : Naked Eyes
2 < V < 5.65 : Optical aid / Naked eyes
-0.96 < V < 2 : Optical aid only
V < -0.96 : Not visible

The western sky was cloudy near the horizon at sunset, scopes were aligned using the 3 planet – Venus, Saturn and Jupiter – and unable to align using the Sun as it was most of the time behind the clouds.

Go out to look for the daily changing moon crescent in early morning, before sunrise, on May 27 until Jun 02 2019 for the Waning and Old Crescent in the Eastern sky. Continue your observation on evening of June 04 until June 10 2019, shortly after sunset, for the New and Waxing Crescent in the Western sky.

Watch for the gorgeous moon glow due to Earthshine on 31 May and 05 June 2019. Most challenging – you may need an optical aids such as telescope or binoculars to spot the slender old Moon crescent on Sunday, 02 Jun 2019 and young thin crescent on Tuesday, 04 Jun 2019. These charts will help you to locate the daily position of the Moon crescent in the sky.

Use our e-Falak online apps:
1. Sun and Moon rise and set timetable
2. Live position of the celestial bodies from BSB, Brunei Darussalam

Please collect and share your pictures of the Moon Crescent on our Facebook or Instagram.