"ECLIPSES AND THE PROMISED MESSIAH"
15th November 1995; revised 16th July 2000
and the Promised Messiah", by Dr Muhammad Aslam Nasir, was placed
Internet under "Review of Religions" in March 1994.)
Dr D L McNaughton is a South African meteorologist
and astronomer working at Dubai Airport in the Meteorological Office. He
is responsible for answering all queries of an astronomical nature and
is considered to be an authority on this subject in the UAE. He is well
known for his valuable contributions of articles in this field to magazines
and journals both locally and internationally for the past several years.
In addition to the following article, at our request, Dr David has examined the occurrence of double-eclipse Ramadans and the statements made by Mirza Ghulam Ahmad Qadiani. His paper will shortly appear in Hamdard Islamicus and will be placed here as well, Insha Allah.
According to Shi-ite accounts, when Imam Muhammed al-Baqir made his prophecy, one of his companions suggested that he might have inadvertently reversed the order of the two eclipses. However, the Imam replied that he had not made a mistake. If indeed (as Dr Muhammad Aslam claims) this Imam had really meant to specify the 13th and 28th of Ramadan, then surely he would have explained that when questioned. Here is one version of how they discussed it:
al-Fadl ibn Shadhan reported [on the authority of Ahmad ibn Muhammad
ibn Abi Nasr] this conversation between Tha'laba al-Azdi and Imam al-Baqir:
"Son of the Apostle of God", I said, "usually an eclipse of the sun happens at the end of the month, whereas an eclipse of the moon occurs in the middle of it?"
"I know what I have said", replied Imam al-Baqir; "these are signs which
have not been witnessed since Adam came down".
Islamic countries occupy a wide range of longitudes between eastern Asia and northwest Africa, so their calendars do not always follow the same Gregorian dates. There is also a marked bias between the northern and southern hemispheres: e.g. it is often easier to spot a new-born crescent from southeast Africa than it is from a Levantine country on the same longitude (or vice versa) - because of the different angles between the ecliptic and the horizon at dusk.
Furthermore, there are other Islamic calendar systems in use which eliminate any dependence on lunar observation: such a calendar (based on a 10631-day cycle) has been adopted by the Bohra community, and (for certain months) by the Saudi Arabian authorities. It often runs one or two days behind calendars which conform strictly to crescent-sighting.
Thus, it may be unproductive to attempt to examine whether or not particular eclipses did in fact occur (or commence ) on the 13th of Ramadan or on the 14th, or whenever, because of the difficulty in deciding which Islamic calendar should be utilised. Nevertheless, there is evidence that the 13th is not the earliest possible date for lunar eclipses - because they can occasionally take place as early as the 12th of an Islamic month (URL/DLMcN, 2000).
However, there is absolutely no doubt that there have been many occasions when a lunar and a solar eclipse have both been witnessed during Ramadan (McNaughton, 1996).
Dr Muhammad Aslam's article contains another time-misconception in his
claim that all eclipses are confined to one particular Islamic day. On
the contrary, it is by no means impossible for an already eclipsed moon
to rise as the sun sets, having been visible earlier on from countries
further east. Similarly, the sun may set while eclipsed - but continuing
to remain eclipsed and still above the horizon elsewhere. Alternatively,
a solar eclipse observed from west Africa or Europe will often begin before
and end after sunset in Pakistan, for example.
If an eclipse-shadow is scheduled to brush the surface of the Earth, then it will still do so even if our planet is suddenly forced to spin faster or more slowly. Admittedly the eclipse timings will be affected (according to a clock running on UTC) - but past records are almost always good enough to confirm dates of occurrence - and indeed to enable scientists to deduce what UTC time-correction is appropriate for each occasion. (The contribution made to that discrepancy by variations in Earth's rotation-rate is known as the "Delta-T" value for the date concerned: these can be estimated for the past much more reliably than for the future).
Despite what Dr Muhammad Aslam implies, year to year variations in the
shape of the moon's orbit can be modelled and calculated extremely well.
The Chapront ELP-2000/82 lunar theory provides one of the best routines
presently available. Accurate cross-checks are provided by numerical integration
of gravitational effects from all important Solar System members. Results
are confirmed later by laser reflectors placed on the moon's surface by
astronauts. It is true that the moon's long-term orbital deceleration is
not known with 100 per cent accuracy - but during the last one or two centuries,
eclipse times computed according to the Chapront algorithm are nevertheless
reliable to within a few seconds.
A professional approach would also have stated what values were assumed
for the Delta-T correction, to allow for the slowing down of Earth's rotation;
it is just possible that other (equally plausible) values could alter at
least one of his dates.
Bao-Lin Liu and A.D. Fiala, 1992: Canon of Lunar Eclipses, 1500 BC- AD 3000. Willmann-Bell Inc., Richmond, Virginia.
M. Chapront-Touze and J. Chapront, 1983: The Lunar Ephemeris ELP 2000. Astronomy & Astrophysics 124, pp. 50-62. Improved expressions are given in a later paper, 1988, in Astronomy & Astrophysics 190, p. 346. Their book Lunar Tables and Programs from 4000 B.C. to A.D. 8000 is published by Willmann-Bell Inc., Richmond, Virginia.
Dar-e-Qatni 1, p. 188. This mentions the prophecy by Muhammed
al Baqir ibn 'Ali ibn Husain regarding eclipses preceding appearance of
the Mahdi - narrated by Amar ibn Shamer, quoting Jaber.
The corresponding Shi-ite versions appear in: Kitab al-Irshad (The Book of Guidance), by Shaykh al-Mufid (d. 1022 AD), Translated by I.K.A. Howard (University of Edinburgh), p. 545, and in Bihar al-Anwar, Majlisi (d. 1699 AD), vol. 113, p. 161.
Explanatory Supplement to the Astronomical Almanac, 1992.University Science Books, Mill Valley, California. It contains a chapter on "Calendars" and another on the "... Rotation of the Earth", as well as discussions on Solar System dynamics (including numerical integration of mutual gravitational effects).
D.L. McNaughton, 1996: Eclipses during Ramadan. Hamdard Islamicus (Karachi) XIX(1). Its 'Table 1' shows double-eclipse Ramadans occurring every 22 or 23 Islamic years. A copy appears in this website, as well as in http://members.fortunecity.com/dlmcn
J. Meeus, 1991: Astronomical Algorithms. Willmann-Bell Inc., Richmond, Virginia. Chapters 45, 47, 48 and 49 discuss the moon's behaviour, including variations in its distance from Earth. Chapter 52 is devoted to eclipses, and chapter 9 to fluctuations in Earth's spin-rate.
J. Meeus and H. Mucke, 1983: Canon of Lunar Eclipses, -2002 to 2526 (2nd edition). Astronomical Office, Vienna.
H. Mucke and J. Meeus 1983: Canon of Solar Eclipses, -2003 to +2526. Astronomical Office, Vienna.
T. R. von Oppolzer, 1887: Canon der Finsternisse. Imperial Academy of Science, Vienna. (1962 English edition published by Dover Publications, New York).
Also see Oppolzer's Great Canon of Eclipses by W.H.C. Carton
- in Sky & Telescope November 1989 , pp. 475-478.
EclipseMaster, SunTracker and MoonTracker are of high quality (enabling eclipses to be examined on a personal computer). They are available from Zephyr Services, Pittsburgh, Pennsylvania.
A companion diskette comes with Meeus's Astronomical Algorithms.
Tables showing dates of Double-Eclipse Ramadans - in Part 5
You are welcome to drop me a note, or else contact David directly:
Dr David L. McNaughton
P. O. Box 1897
United Arab Emirates.
UK telefax: +44-870-1680423