ArticlesBy Hydari28 August 20255 min read

Crescent, Time System, and Calendar: A Qur’anic and Scientific Study

Write by Shaikh Jawad Habib

Introduction

The Holy Qur’an invites humankind to reflect upon the universe and guides them to derive both material and spiritual benefits from natural phenomena. Among these phenomena, one of the most significant is the crescent (hilāl).

Allah Almighty, in Surah al-Baqarah (2:189), Surah Yūnus (10:5), and Surah al-Isrā’ (17:12), speaks of the sun, the moon, and the system of day and night, designating them as standards for time, calendars, and acts of worship.

This article, based on these verses, presents a comprehensive study that combines:

Classical and modern Qur’anic exegesis (tafsīr),
Narrations from Ahl al-Bayt (a),
And contemporary scientific research,

to demonstrate that the Qur’an’s guidance is universal and timeless.

1. Surah al-Baqarah (2:189) and the Question of the Crescent

﴿يَسْأَلُونَكَ عَنِ الْأَهِلَّةِ قُلْ هِيَ مَوَاقِيتُ لِلنَّاسِ وَالْحَجِّ﴾

"They ask you about the crescents. Say: they are time markers for people and for the Hajj."

Hilāl, Time System and Calendar: A Qur’ānic and Scientific Study

(a) Background
The Arabs frequently asked the Prophet ﷺ why the moon starts as a thin crescent, gradually becomes full, and then wanes. Some were curious about its form, while others sought its function. The Qur’an, instead of delving into cosmic philosophy, gave a direct answer: the crescent exists as a calendar for human life and acts of worship.

(b) In the light of narrations
Imam Muhammad al-Bāqir (a) said:
"The crescent is a means of determining time for people in Hajj, fasting, marriage, and financial matters." (Tafsīr al-Qummī)

(c) Scientific explanation
According to astronomy, the crescent appears due to the changing positions of the Earth, Moon, and Sun. This change follows a fixed system known as the lunar cycle, lasting approximately 29.53 days. Modern scientists use lunar phases to calculate months, and the lunar calendar is based upon this system. The Qur’an expressed this scientific truth in a concise and universal way over 1400 years ago.

2. Surah Yūnus (10:5) and the Astronomical System

هُوَ الَّذِي جَعَلَ الشَّمْسَ ضِياءً وَالْقَمَرَ نُوراً...

"He it is who made the sun a source of radiance and the moon a light, and determined its phases so that you may know the number of years and calculation. Allah created this in truth and explains His signs for those who know."

(a) Key insight
The Qur’an highlights two distinctions:

The Sun is ḍiyā’ (a self-luminous source of light).
The Moon is nūr (a reflective light).

This scientific reality was unknown to humanity until recently but was declared in the Qur’an centuries ago.

(b) Scientific confirmation
According to NASA and modern astrophysics:

The Sun is a massive G-type main-sequence star, generating energy through nuclear fusion.
The Moon produces no light of its own; it merely reflects sunlight.

This perfectly matches the Qur’an’s terminology.

3. Surah al-Isrā’ (17:12) and the System of Day and Night

﴿وَجَعَلْنَا اللَّيْلَ وَالنَّهَارَ آيَتَيْنِ...﴾

"And We made the night and the day two signs. We erased the sign of the night and made the sign of the day bright, so that you may seek the bounty of your Lord and know the number of years and calculation. And We have explained everything in detail."

(a) Objection and response
Some critics question why the Qur’an says the "sign of the night was erased." The answer: night is devoid of natural brightness, whereas the day is full of illumination. This is exactly what modern astronomy confirms: the Earth’s rotation causes alternating light and darkness.

(b) Scientific evidence

The Earth’s rotation produces day and night.
This rotation is so precise that humans can measure time down to a fraction of a second.
Even atomic clocks are ultimately calibrated with celestial movements.

4. Islam’s Distinctive System and Modern Science

The uniqueness of the Islamic calendar lies in its reliance on natural signs:

The day begins at sunset.
The month begins with the visible crescent.
The year is calculated by lunar months.

These are universally observable standards, accessible to both literate and illiterate people. By contrast, solar calendars and atomic measurements are accessible only to specialists.

5. Doubts and Their Answers

Doubt 1: Is the lunar year incomplete since it is 11 days shorter than the solar year?
Answer: This is not a deficiency but a unique feature, ensuring that acts of worship (like Ramadan and Hajj) fall in different seasons, testing believers under varying circumstances.

Doubt 2: Isn’t modern scientific equipment more accurate for measuring time?
Answer: True, but the Qur’an provides a simple and universal standard for all people, not just experts. Scientific precision tools serve specialists, whereas lunar observation is accessible to everyone.

Conclusion

The three Qur’anic verses point to a comprehensive system:

Crescent (hilāl): A standard for months and worship.
Sun and Moon: Instruments for years and calculations.
Day and Night: Organizers of human life and activity.

This system is so perfect that even modern science operates upon the same foundations. The difference lies in the perspective: the Qur’an presents these phenomena as guidance and signs of divine order, while science studies them as natural observations.

The Qur’an’s final message is: "Enter houses through their proper doors" (al-Baqarah 2:189), meaning that whether in worship, knowledge, calendars, or daily life, every system must be approached through the right, natural, and divinely ordained way.