Moon Sighting and the Islamic Calendar
Following a suggestion from a friend of mine to further explain the Islamic Calendar which is based on moon sighting that determines the beginning and the end of each month, I have gathered here some information from different sources which I hope will be of some help.
Islamic months begin at sunset on the day of visual sighting of the lunar crescent. Even though visual sighting is necessary to determine the start of a month, it is useful to accurately predict when a crescent (Hilal in Arabic) is likely to be visible in order to produce lunar calendars in advance. Although it is possible to calculate the position of the moon in the sky with high precision, it is often difficult to predict if a crescent will be visible from a particular location.
Visibility depends on a large number of factors including weather condition, the altitude of the moon at sunset, the closeness of the moon to the sun at sunset, the interval between sunset and moonset, atmospheric pollution, the quality of the eyesight of the observer, use of optical aids etc. Since ancient times, many civilizations and astronomers have tried to predict the likelihood of visualizing the new moon using different 'minimum visibility criteria'. However, all these criteria are subject to varying degrees of uncertainty.
The New Moon phase is defined to be the moment when the moon is almost directly between the Earth and the Sun. At this moment the moon's dark surface faces the Earth. The New Moon is therefore completely invisible. The date and time of this invisible New Moon is commonly found in almanacs, newspapers and calendars.
The Islamic month begins with the visible First Crescent and not with the invisible New Moon. The first Crescent is usually sighted in the western sky just after sunset on the first or second evening after the New Moon phase. The sighting depends on the age of the crescent, the time difference between sunset and moonset and the angular distance between the sun and the moon.
We should not confuse the New Moon with the visible thin crescent. We should realise that a crescent following a lunar month of 30 days will look larger and stay longer than the crescent following a month of 29 days.
If the moon is high up in the sky or sets late, it is not proof of the fact that it appeared the previous night. However, if the moon is seen before noon, that day will be treated as the 1st of the month (i.e. it will be assumed that the new moon appeared the previous night). Similarly if there is a halo (crown of light) around it, it goes to show that the new moon appeared the previous night.
Moon sighting is highly observed especially to determine the beginning of the Holy month of Ramadhan. In fact the sighting of the crescent moon at the end of the month of Shaaban signifies the beginning of the holy month of Ramadhan. Eid ul-Fitr is celebrated at the end of Ramadhan following the sighting of the Shawaal crescent on the previous evening.
The thin crescent moon may be seen after sunset once the sky is sufficiently dark. However, false sightings (i.e. honest mistakes) are common since many objects in the sky can be mistaken for the lunar crescent especially if there is a heightened sense of expectation.
Islamic months begin at sunset on the day of visual sighting of the lunar crescent. Even though visual sighting is necessary to determine the start of a month, it is useful to accurately predict when a crescent (Hilal in Arabic) is likely to be visible in order to produce lunar calendars in advance. Although it is possible to calculate the position of the moon in the sky with high precision, it is often difficult to predict if a crescent will be visible from a particular location.
Visibility depends on a large number of factors including weather condition, the altitude of the moon at sunset, the closeness of the moon to the sun at sunset, the interval between sunset and moonset, atmospheric pollution, the quality of the eyesight of the observer, use of optical aids etc. Since ancient times, many civilizations and astronomers have tried to predict the likelihood of visualizing the new moon using different 'minimum visibility criteria'. However, all these criteria are subject to varying degrees of uncertainty.
The New Moon phase is defined to be the moment when the moon is almost directly between the Earth and the Sun. At this moment the moon's dark surface faces the Earth. The New Moon is therefore completely invisible. The date and time of this invisible New Moon is commonly found in almanacs, newspapers and calendars.
The Islamic month begins with the visible First Crescent and not with the invisible New Moon. The first Crescent is usually sighted in the western sky just after sunset on the first or second evening after the New Moon phase. The sighting depends on the age of the crescent, the time difference between sunset and moonset and the angular distance between the sun and the moon.
We should not confuse the New Moon with the visible thin crescent. We should realise that a crescent following a lunar month of 30 days will look larger and stay longer than the crescent following a month of 29 days.
If the moon is high up in the sky or sets late, it is not proof of the fact that it appeared the previous night. However, if the moon is seen before noon, that day will be treated as the 1st of the month (i.e. it will be assumed that the new moon appeared the previous night). Similarly if there is a halo (crown of light) around it, it goes to show that the new moon appeared the previous night.
Moon sighting is highly observed especially to determine the beginning of the Holy month of Ramadhan. In fact the sighting of the crescent moon at the end of the month of Shaaban signifies the beginning of the holy month of Ramadhan. Eid ul-Fitr is celebrated at the end of Ramadhan following the sighting of the Shawaal crescent on the previous evening.
The thin crescent moon may be seen after sunset once the sky is sufficiently dark. However, false sightings (i.e. honest mistakes) are common since many objects in the sky can be mistaken for the lunar crescent especially if there is a heightened sense of expectation.
posted by Hannibal | 1:50 PM
1 Comments:
Glad that you find the post on Moon Sighting interesting and sorry for this delay. Well if you further information on how and when the crescent came to symbloize Islam here is a link which I think will answer your question: http://islam.about.com/library/weekly/aa060401a.htm
Post a Comment
<< Home