Why is it not possible to see the Shawwal crescent after sunset on Saturday, March 29, in Jordan and the Islamic world?

Arab Weather - Dr. Ammar Al-Sakaji, President of the Jordanian Astronomical Society, said that most Arab and international astronomical institutions and centers agree on the accurate astronomical data for the Shawwal crescent moon for the year 1446 AH. For example, in the Jordanian capital, Amman, the central conjunction (new moon) will occur at 1:58 pm on Saturday, March 29, 2025. The angle of elevation of the crescent above the horizon at sunset is 1.4 degrees, and the angle between the moon and the sun (elongation) is 2.2 degrees. The crescent will remain above the horizon for 10 minutes, its age will be 4 hours and 56 minutes, and its illumination degree will be 0.1 %.

These data indicate that the crescent will be very thin and faint above the horizon in all Arab cities and capitals after sunset, albeit for varying durations. In Cairo, it will remain visible for 11 minutes, in Jerusalem for 10 minutes, in Mecca for 7 minutes, and in Marrakesh for 18 minutes .

Astronomical calculations: The crescent moon is above the horizon, but it is "impossible " to see it.

Although astronomical calculations confirm that the crescent has been born and is above the horizon after sunset on Saturday, March 29, in most of the Islamic world, it will be “impossible” to see it with the naked eye or with telescopes in Jordan and the Islamic world, according to various historical and modern astronomical criteria, such as the Babylonian criterion, the Al-Battani criterion, the Elias criterion, the Schaefer criterion, the Dungeon criterion, the Yallop criterion, the Allawi criterion, and the Odeh criterion .

This conclusion is based on the cumulative databases of the Islamic Crescent Sighting Project, which emerged from the Jordanian Astronomical Society in the 1990s and later expanded into an independent global project under the supervision of the International Astronomical Center. Engineer Mohammed Odeh developed this project through accurate statistical and observational studies, which he reinforced with data from Arab and Islamic astronomical conferences that addressed the criteria for crescent sighting in detail .

Analyzing the theoretical data for the Shawwal crescent on Saturday, March 29, and comparing it with the Islamic Crescent Sighting Project's database, which includes more than 3,000 documented sightings, shows that sighting the crescent after sunset will be "impossible" in Jordan and the Islamic world. According to the Odeh criterion, which is based on 737 documented sightings and has been supported by hundreds of subsequent global observations, the "maximum values" recorded by the Islamic Crescent Sighting Project show that :

• The crescent stayed for 10 minutes, and the shortest duration of a crescent seen with the naked eye was 29 minutes .
• The crescent's age is approximately 5 hours, and the shortest age of a crescent seen with the naked eye was 15 hours and 33 minutes .
• The elongation is 2.2, and the lowest elongation observed with the naked eye was 7.6 degrees .

The minimum duration of a crescent seen with telescopes was 20 minutes, the minimum age of a crescent seen with telescopes was 13 hours, and the minimum elongation seen with telescopes was 6.0 degrees .

The International Astronomy Center issues an astronomical report on the conditions for sighting the Eid al-Fitr crescent moon for 1446 AH.

Determinants of Crescent Observation: Scientific and Astronomical Challenges

There are several astronomical and physical factors that make observing the crescent moon on Saturday, March 29, 2025 “impossible,” including :

1. Atmospheric interference and distortions

• Increased atmospheric mass: The light of the crescent moon passes through a dense atmospheric layer due to its very low altitude, which leads to blurring the image .

• Weather fluctuations: Air disturbances near the horizon cause the image to shake and become unstable, making it difficult to see the crescent .

2. Light scattering and absorption

• Rayleigh scattering: The scattered blue light affects the clarity of the crescent, reducing its contrast with the sky .

• Atmospheric absorption: causes the crescent to dim due to the absorption of short wavelengths .

3. refraction phenomenon

• Crescent position deviation: The light coming from the crescent is subject to atmospheric refraction, which makes it appear in a different location than its actual location .

• Distortion of shape: The crescent may appear distorted or stretched due to atmospheric refraction .

4. low contrast

• Sky brightness at sunset: The sky near the horizon is brighter, making the crescent almost invisible due to poor contrast .

5. transparency of the sky

• Humidity and water vapor: affect the clarity of the crescent and reduce the possibility of observing it .

• Clouds: They may completely obscure the crescent moon .

6. thermal effects

• Thermal disturbances: lead to image distortion due to thermal changes in the air .

Can the crescent moon be observed with giant ground-based or space-based telescopes?

First: Ground-based telescopes

Even the largest ground-based telescopes face additional challenges in observing the crescent moon due to :

• Tracking accuracy: Low crescent angles require fine adjustment that may be difficult on large telescopes .

• Mechanical obstacles: Some telescopes cannot track objects very close to the horizon .

• Not designed for crescent observation
• Most of them are outside the Arab region, which creates a time difference problem.

Second: Space telescopes

• Hubble Telescope (HST): It is not designed to observe the crescent moon due to its angular proximity to the sun, and the danger to sensitive sensors .

• James Webb Space Telescope (JWST): It has high sensitivity in infrared radiation, but it is not designed to observe objects that are close to the sun, because the intense glare of the sun may damage the sensitive sensors .

• Launching a solar telescope into space, such as SOHO : It uses specialized techniques (coronographs) to block sunlight. It can be a useful tool for observing the crescent moon, but it is preferable for it to be at the L2 Lagrange point.

The Future of Crescent Observation: Solutions and Scientific Developments

Crescent observations can be improved using advanced technologies, such as artificial intelligence for predictive modeling, adaptive optics for real-time correction of atmospheric distortions, and observations using different radiation levels. The development of ground-based and space-based solar telescopes could help astronomers develop new methods for observing the crescent moon in challenging conditions .

We would like to emphasize that the Jordanian Astronomical Society is not the official body authorized to announce the dates of religious holidays and occasions. Determining the beginning of the lunar months falls under the purview of His Eminence the Grand Mufti of the Hashemite Kingdom of Jordan and the Council of Iftaa, Research and Islamic Studies, which are the official authority for announcing the beginnings of the lunar months in the Hashemite Kingdom of Jordan .