This year, as in previous years, the end of Ramadan and Eid al-Fitr—one of our two important religious festivals—are being observed on different days in different countries.
The disagreement over announcing the date of Eid al-Fitr, which is a national holiday in all Islamic countries, has raised many questions. Because determining the date is connected with the astronomical phenomenon of the Moon emerging from conjunction (the new-moon phase), many people ask: in an age when humans can travel through space, and when our leading astronomers can calculate and predict the motions of celestial bodies and astronomical events years in advance with very high precision, can the date of Eid al-Fitr not be calculated accurately beforehand and placed in calendars so that people can plan around this national holiday?
Visibility of the Shawwal 1433 crescent on the evening of 29 Mordad 1391, based on the Yallop criterion (generated with Accurate Times).
Click the image for a larger version.
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Yallop Accurate Times) |
You can read the discussion of the date of Eid al-Fitr in 1392 here.
Dr. Iraj Malekpour of the Institute of Geophysics at the University of Tehran, who for more than a quarter of a century officially held responsibility for calculating and determining religious times and calendar occasions, says that historical evidence shows Iranians were able to calculate the beginnings and endings of months accurately as far back as four thousand years ago. Today, too, the astronomical moment at which the Moon leaves conjunction can be calculated and announced precisely. [source]
In fact, the problem that arises in determining the date of Eid al-Fitr comes from differences of opinion among religious jurists and authorities, rather than from the scientific instruments or methods used to determine the astronomical event.
The disagreement concerns two concepts known as the “birth of the Moon” and the “sighting of the Moon.” “Birth of the Moon” means the moment the Moon emerges from conjunction, while “sighting of the Moon” refers to the time when the Moon, after leaving conjunction, can actually be seen. The interval between birth and visibility is usually twelve to fourteen hours.
Some jurists, particularly Sunni jurists, announce the end of Ramadan and the arrival of Eid al-Fitr once they have information that the new Moon has been born. By contrast, the overwhelming majority of Shi'a jurists regard the sighting of the new Moon as the relevant point for the arrival of Eid al-Fitr.
Shi'a jurists also differ over the geographical area for which a sighting is valid. Some hold that once reliable witnesses testify to seeing the new Moon in one location, Eid al-Fitr can be declared everywhere. Others believe that a sighting in one region is valid only for that region and nearby areas.
Some argue that crescent sighting is a celestial rather than terrestrial matter, and therefore that if the Moon is seen at one point on Earth, the sighting should be valid for everyone. In response, others argue that this view relies only on abstract reasoning while setting aside direct observation. Earth has different horizons, and the direction and possibility of observing the crescent for one half of the globe differ from those for the other half. Crescent visibility therefore depends on the horizon of observers living on Earth; without considering terrestrial horizons, the concept of sighting has no practical meaning for people with different horizons.
According to this reasoning, the Moon’s mere emergence from conjunction cannot by itself establish crescent visibility for everyone on Earth. Likewise, instruments such as satellites, which operate outside the terrestrial horizon, cannot establish a sighting for every region. In crescent observation, factors in addition to conjunction are involved, and the astronomical horizon must be taken into account.
This raises another question: why do countries in which the sighting requirement has been set aside and the astronomical birth of the Moon is used as the basis—a phenomenon that occurs at one instant for the whole Earth—still announce Eid al-Fitr on different dates?
Dr. Malekpour believes that Arab countries, particularly Saudi Arabia, which serves in some respects as a reference point for Sunni Muslims, have not always carried out the astronomical calculations for determining the beginning of the new month correctly and accurately.
He says that in 1355 SH, a group of experts from the Saudi royal court came to Iran to investigate why Iran did not follow Saudi Arabia’s lunar calendar. When, at the direction of the Iranian government of the time, they met Iranian specialists in the mathematics department of the University of Tehran’s Faculty of Science, it became clear to them that the Iranian lunar calendar was more accurate than the Saudi lunar calendar.
An organization called the Muslim World League (Rabitat al-Alam al-Islami), based in Mecca, once brought together representatives of Islamic countries. The meeting decided that Eid al-Fitr should thereafter be announced simultaneously in all of those countries. Nevertheless, in subsequent years each country again announced its own date, and after years had passed the decision made at the Mecca meeting came to nothing. Each country therefore continued to act according to its own determination. [source]
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OdehYallopSAAO Accurate Times) |
Visibility of the Shawwal 1433 crescent on the evening of Saturday, 28 Mordad 1391, according to the Odeh (top), Yallop (middle), and SAAO (bottom) criteria (generated with Accurate Times).
Click the image for a larger version.
This year, as shown in the figure above, the Shawwal crescent should be visible to the unaided eye throughout Iran on the evening of Sunday, 29 Mordad. Therefore, in Iran, Eid al-Fitr will most likely fall on Monday, 30 Mordad 1391 SH, corresponding to August 20, 2012.
More specifically, according to the accompanying figure calculated using the three recognized Odeh, Yallop, and SAAO criteria, observing the Shawwal crescent anywhere in Iran on Saturday, 28 Mordad is not possible.
According to the Odeh criterion, the new crescent on Saturday can readily be seen only in central and southern Africa, the southern United States, Australia, and countries in South and Central America. Across much of Southeast Asia, northern Australia, southern India, the Arabian Peninsula, northern Africa, and the central United States, the crescent can be seen only with optical aid. In the remaining parts of the world—including Iran—the new Moon cannot be observed that Saturday even with optical aid, according to the Odeh criterion.
According to the Yallop criterion, which the article describes as having greater accuracy than the other criteria on the basis of previous observations, the new crescent on Saturday can readily be seen only in southern Africa and Central and South America. In southern parts of central Africa, western Australia, Mexico, and parts of several southern U.S. states, unaided-eye visibility is possible only under very favourable atmospheric conditions, with neither cloud nor dust. In northern parts of central Africa, central Australia, and much of the southern United States, optical aid may be required. In northern Australia, the Philippines, Indonesia, Yemen, and southern parts of Egypt, Libya, and Algeria, as well as a narrow strip of the central United States, visibility is possible only with optical aid. In the rest of the world, including Iran, visibility is not possible even with optical aid.
According to the SAAO criterion, the new crescent on Saturday can readily be observed only in central and southern Africa, Central and South America, and eastern Australia; in the other regions of the world, observation is not possible.
Finally, atmospheric and site conditions—such as the elevation of the observing location—also have a major influence on the probability of a sighting and can sometimes make observation possible even under otherwise very difficult conditions.