Sighting of the New Moon

Fasting is prescribed in the month of Ramadhan. The Islamic calendar is Lunar. Ramadhan is the ninth month of the Islamic calendar. The advantage of the lunar based calendar is that the observation of the months is easily possible for all people. One needs to be acquainted with astronomy or refer to a reliable calendar to find out about the solar based calendar. Otherwise, you will not have any idea when, for example, the first day of October is going to be.

The lunar calendar can easily be observed by all people by sighting the moon. The moon is the only natural satellite of earth. The moon is the second brightest object in Earth’s sky, after the Sun. Thus, its observation requires not astronomical equipment. Even the crescent moon is nearly always visible by naked eyes.

The Moon has no light and it shines by reflecting the light of the Sun. The moon moves in an elliptical (oval-shaped) orbit around Earth at an average speed of 3,700 km/h. For the Moon to go from one phase to the next similar phase-as seen from Earth-it requires 29 days 12 hours and 44 minutes. This period is called a lunar month. On the observation of the new moon with a naked eye, the lunar month will be either 29 days or 30 days depending on the angle and the height at which the new moon is sighted.

The Moon shows progressively different phases as it moves along its orbit around the Earth. Half the Moon is always in sunlight, just as half of Earth has day while the other half has night. In the phase called the new moon, the near side is completely in shadow. About a week after a new moon, the Moon is in first quarter, resembling a luminous half-circle; another week later, the full moon shows its fully lit near side; a week afterwards, in its last quarter, the Moon appears as a half-circle again. The entire cycle is repeated each lunar month.

With a bit of experimental observation any individual will be able to identify the age of the moon and hence the day and the month he is in.

In order to facilitate the observation of the Islamic rituals for all Muslims, the Islamic calendar is lunar based. The Almighty Allah states in the Qur’an:

“They ask you about the new moons. Say: these are signs to mark fixed periods of time for mankind and for the pilgrimage.” [2:189]

It is narrated from the Prophet of Islam (S) that ‘the fixed period of time’ is for observing the fasting of Ramadhan and breaking of the fast at the end of the month as well as for observation of the Hajj ceremony.

Fast When You Have Observed the New Moon

Numerous Hadith state: “Start the fasting by sighting the crescent moon (of Ramadhan) and stop fasting by sighting the crescent moon (of Shawwal).”

Authentic narrations also state that if the new moon was not visible due to the clouds or similar obstacles, one must complete the days of the month to 30 days. If a day is doubtful whether it is the last day of Sha’ban or the first day of Ramadhan, it is Haraam to fast with the intention of the first day of Ramadhan. It is however recommended to observe the fasting of that day but with the intention of the last day of Sha’ban as a Mustahab fasting.

One cannot make up his/her Qada (lapsed) fasting on that day either. Similarly, one must continue fasting of the doubtful day at the end of Ramadhan, until it is proven to be the day of Eid. If one however completed the fast and then found out that it was the day of Eid, there is no sin on him as his intention was not to fast on the day of Eid. In short, the general rule about doubtful days is to complete the day of the month to 30 days.

“You must complete the number (of days).” [2:185]

Ali Ibn al-Qasani narrated: “I wrote to Imam As-Sadiq (a.s) while I was in Madina if we had to fast on the day which is doubtful whether it is the first day of Ramadhan or the last day of Sha’ban. The Imam (a.s) replied back:

‘Doubt shall not enter certainty. Observe fasting when you see the new moon (of Ramadhan) and break your fast when you see the new moon (of Shawwal).’”

Criteria for Sighting the Crescent Moon

The Moon is a celestial body. In order for us to observe a celestial body in the sky two main criteria are involved. 1) The object must be bright enough, 2) Because the earth is spherical; the altitude of the object at the horizon must be high enough to reach the angle of human eye sight. [Fig.1]

Figure 1. a new crescent moon

Although the Moon is the second brightest body in the Earth’s sky, it has no light from itself. Thus, in order for the new crescent moon to be visible it has to be at a certain angle with the Sun to reflect the sunlight. This will be achieved if the moonset is at least 47 minutes after the sunset.

That means the age of the new moon at local sunset must be 24 hours plus or minus 2 hours. In astronomical terminology this means the difference in azimuth between Sun and Moon shall not be less than 25 degrees while the Moon’s altitude at sunset is not less than 12 degrees.

Although there are other criteria also involved in sighting the crescent moon such as brightness of the evening sky, contrast requirements of the eye, atmospheric reflection, etc, the above two mentioned criteria are the main.

We also have to bear in mind that the Moon usually rises from the west whereas the sun rises from the east. Thus, the probability of visibility of the new moon decreases to the east. That means people at the western parts of the world will be the fist to sight the new moon whilst the Far East being the last. This will sometimes result in one day difference between the western sight and the eastern sight of the moon.