Why does the crescent appear when Ramadan comes?

- Could you give detailed information about hilal (crescent)?
- In what other issues is it important?

Dear Brother / Sister,

Along with the solar year and months, there also exist the lunar year and months.

The months of the lunar year begin with the sighting of the crescent in principle.

Therefore, if the crescent is seen on the western horizon following sunset on the evening of the twenty-ninth day of the months of Shaban and Ramadan, the new lunar month will start and the next day will be the beginning of fasting and the eid (feast) respectively; if the crescent is not seen, that month will be regarded as thirty days.

Thus, we understand the beginning or the end of a lunar month through the crescent seen after sunset at the end of that month. The crescent seen at the end of Shaban means that the next day is the first day of Ramadan. The crescent seen at the end of Ramadan indicates that the next day is eid and that the month of Ramadan is over and the month of Shawwal has begun.

After this brief information, let us have a look at the details of the issue:

As it is pointed out in the Quran (al-Isra 17/12; al-Furqan 25/61; Nuh 71/16), the moon itself is not a source of light; the brightness seen from the earth consists of the reflection of sunlight on the moon’s surface.

Depending on the angle at which the illuminated surface of the Moon from the Earth due to its position with the Sun, this brightness is sometimes seen from the earth as a crescent, sometimes as a semicircle or as a full moon; sometimes it is not seen at all. Since the Moon’s rotation period around the Earth and its rotation period around its own axis are equal, the same surface is always observed from the Earth.

When the Moon rotates around the Earth and is located in a straight line between the Sun and the Earth, it is called conjunction (ijtima’). Meanwhile, the Moon rises and sets together with the Sun and cannot be seen from the earth because its illuminated surface faces the Sun completely and its dark surface faces the Earth.

However, since the Moon rises and sets later than the previous day each day, it soon leaves this line and begins to set later than the Sun. Thus, when the angle between the Sun and the Moon reaches a sufficient size for the light reflected on the Moon’s surface to be visible (ru’yah)) from the earth, the Moon begins to be seen as a crescent on the western horizon after sunset.

The night when the crescent is seen belongs to the new month, not to the previous month because with the visibility of the crescent on the western horizon, the previous month ends and the new month begins.

In the first days of the new moon, since the Sun rises and sets before the Moon and it moves in front of the Moon, the Moon receives the sun’s rays from below compared to us and its lower surface is illuminated. Therefore, after sunset, the ends of the crescent of the new moon on the western horizon point upward (to the sky).

In the last days of the month, since the Moon rises and sets before the Sun, it can only be observed on the eastern horizon with its ends facing west before the Sun rises, and the last crescent of the Moon cannot be observed on the western horizon. If the last crescent of the moon could be observed on the western horizon before sunset, it would be seen that the ends of the crescent point downward (to the horizon) because at this time, the Sun is above the horizon, higher than the Moon, and the Moon is illuminated from above.

The Moon completes its rotation around the Earth in 29.530589 days (29 days 12 hours 44 minutes 2.8 seconds). This period, which is equal to the time between two consecutive repetitions of any phase of the Moon, such as a full moon or conjunction, is called the “astronomical month” (conjunction month, synodal month).

Accordingly, a lunar year is 29.530589×12=354.367068 days theoretically. However, since the number of days cannot be fractional, months are sometimes shown as twenty-nine and sometimes thirty days in the lunar calendar.

Since ancient times, the periodic and regular movements of the Sun and the Moon have been used as a measure and indicator of time.

In addition to their many benefits, it is also pointed out in the Quran that the Sun and the Moon are also used to know and calculate time:

“He (Allah) it is that cleaveth the day-break (from the dark): He makes the night for rest and tranquility, and the sun and moon for the reckoning (of time)...” (al-An’am 6/96)

“It is He (Allah) Who made the sun to be a shining glory and the moon to be a light (of beauty), and measured out stages for her; that ye might know the number of years and the count (of time)…” (Yunus 10/5)

However, since the Moon is in the same phases periodically for regular and fixed periods, it is more convenient than the Sun for determining time. Although day and night, day and year can be partially understood from the movements of the Sun, there is no specific sign or measurement in the movements of the Sun for the duration of the month. As a matter of fact, the number of days of the months in the year determined according to the movements of the Sun is determined nominally, not by a natural comparison.

It is stated in the Quran that the regular movement of the moon in the sky is the time measurements for people and especially for hajj (al-Baqara 2/189), and that when the heavens and the earth were created, its movements were arranged to form twelve months (at-Tawba 9/36).

Except for prayer times, time to start fasting and iftar time, it is seen in the direct and indirect expressions of the Quran, hadiths and the Islamic tradition formed within this framework that the lunar months are taken as basis in determining the times and durations of deeds of worship that are dependent on certain times during the year, such as Ramadan fasting, hajj (pilgrimage), zakah, alms of fitr, sacrificing animals and Eid prayers, along with religious transactions such as oath, ila (forswearing one’s wife), and iddah.

As a matter of fact, the Prophet (pbuh) said, “Allah Almighty made the crescents time measurements for people. Then, start fasting when you see the crescent, and break your fast when you see it again.” (Musnad, IV, 23, 321; Daraqutni, II, 163; Hakim, I, 585)

Since the accurate determination of the time or duration of such worship and transactions, for which the lunar months are taken as measurements, depends on the correct determination of the beginnings of the lunar months, the sighting of the crescent has long had an important place in the Islamic tradition.

It is mustahab to pray as follows after uttering takbir when the crescent is seen:

“Oh Allah! Bless this new crescent for us in belief, Islam, security, abundance and well-being. O crescent of goodness and maturity! Your Lord and our Lord is Allah; bring us goodness and luck.” (Tirmidhi, Daawat, 51)

Determining the boundaries of the lunar months can be done by the observation of the crescent, or by calculation if it is done correctly.

Today, the results obtained by astronomy and astronomical calculations are accurate.

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