sECLIPSES DURING RAMADAN
---------------------
John Pazmino
NYSkies Astronomy Inc
nyskies@nyskies.org
www.nyskies.org
2020 October 3
Introduction
My article 'Islamic moon and eclipses' in the NYSkies web noted
that the pattern of eclipses during Ramadan neds deeper inquiry. The
lunar eclipses, which I emphasized, come in seasons spaced 21 or so
civil years apart. Of greater curiosity is the restriction of lunar
eclipses in Ramadan to a set of three bands of civil dates. These take
turns for Feb-Mar, Jun-Julm Oct-Nov.
within a few days of the article's announcement in the October
2020 edition of NYC Events, a few readers suggested sources for
further investigation. All were overall equally good. All were webs
rahter than printed matter.
I found that I didn't have to condense or combine these sources,
being that each was reasonably ample for itself. Here Ireprint here one of
them, by Dr David McNaughton, who gives tables of years when
Ramadan had both a lunar and solar eclipse. The last instance was in
civil year 2003. In the tables AH is Anno Hegrae, the Islamic year,
and AD is Anno Domini, the civil year.
Except for layout alignment and trivial editing the article here is
McNaughton's. The first two sections explain the mechanics of eclipses
and may be skipped by eclipse-litterate readers. Start eith 'Prefered
dates for Ramadan eclipses'.
= = = = =
Eclipses during Ramadan
=====================
by David L. McNaughton
In "Hamdard Islamicus" (Karachi, Pakistan), vol. XIX no. 1 (Spring
1996): pp. 81-86.
Characteristics of Solar Eclipses
--------------------------------
The sight of a total eclipse of the sun is an awe-inspiring
experience. Daylight quickly becomes near-darkness, and all birdsong
ceases as those creatures are deceived into thinking that night has
fallen.
However, only a small area of the globe enjoys the privilege of
admiring the total phase of such an eclipse whenever one sweeps across
our planet. Even so, astronomers can now predict accurately those
places and their times - enabling many of them to go and witness such
an event. Total solar eclipses provide by far the best opportunity to
study the seething atmosphere in the sun's outer atmosphere, so
scientists are always present to take photographs and carry out
spectrographic and other measurements.
A solar eclipse can occur only at New Moon, but not every New Moon
produces a solar eclipse. That is because the plane containing the
lunar orbit is inclined to the plane defined by Earth's much larger
orbit round the sun (called the "ecliptic" plane). Thus, at the
instant of its birth a New Moon's position in the celestial firmament
is usually either above or below the sun: under those circumstances
the sun cannot become eclipsed.
About twice every year, however, New Moon happens to take place
just as the moon is passing through the ecliptic plane. That produces
almost perfect alignment of the three celestial bodies, enabling the
moon to hide the sun from some terrestrial observers. The moon's umbra
(full shadow) traces out a comparatively narrow path across Earth's
surface; people there see a total eclipse. At the same time, a much
larger area of our globe falls within the moon's penumbra (its partial
shadow); observers there are close enough to the axis of alignment for
the sun to appear partially covered.
Sometimes the umbra just misses the Earth, but a portion of our
planet still lies within the penumbra - experiencing a partial
eclipse. On rare occasions the umbra can just graze the Earth - but
without the axis of the moon's shadow-cone ever intersecting the
surface of our planet: such eclipses are termed "total but non-
central".
If the lunar orbital plane remained pointing in the same
direction, then solar eclipses would always occur near the same
Gregorian date, year after year. However, the lunar orbital plane
gradually swings round, completing a revolution every 18.6 years;
inevitably that movement affects the dates of solar eclipses. The
result is that the interval between them tends to be either six or
(less commonly) five /lunar/ months. That is why solar calendar dates
of eclipses are often slightly earlier than ones experienced during
the previous year.
Lunar Eclipses
------------
To produce a lunar eclipse, Earth must lie between the sun and
moon. Once again, alignment needs to be nearly exact, so (like a solar
one) this sort of eclipse is possible only when the moon is on or near
the ecliptic plane. This time it is Earth which is casting the shadow
-sometimes over the entire lunar disc (total eclipse); on other
occasions on just a portion of it (partial eclipse). A lunar eclipse
can take place only at Full Moon, and may be observed from absolutely
anywhere in Earth's night-hemisphere.
About two weeks before or after a lunar eclipse, there is always
some sort of solar one - because alignment on the first occasion means
that there will still be sufficient alignment for the second. In fact,
in rare instances it is even possible to have a small partial solar
eclipse just prior to the beginning of an Islamic month, followed by a
lunar one in mid-month, and then by another small partial solar
eclipse near the end of the same month. (A "small" partial eclipse
affects a very restricted area of Earth's surface, with just a minute
fraction of the solar disc appearing to be covered).
Preferred dates for Ramadan Eclipses
----------------------------------
Every now and again, there is an eclipse during the Holy Month of
Ramadan - either a lunar eclipse near the middle of the month or a
solar one near the end. Islamic months cannot begin until a day or two
after a sun-moon conjunction (to give time for the crescent to become
visible), so it is not possible to experience a solar eclipse at the
beginning of an Islamic month.
A detailed analysis of Ramadan eclipses reveals a surprising
pattern: they seem to be restricted to certain dates in the Gregorian
calendar. Every total lunar eclipse which has ever occurred during
Ramadan, for example, has fallen within one of three short intervals:
22nd February to 13th March, 20th June to 11th July, or 16th October
to 7th November (1), which together add up to less than 20 per cent of
the entire year. (To maintain continuity, dates recorded in the old
Julian calendar prior to AD 1582 (or 1752) were converted to
"extrapolated" Gregorian-style dates for this particular
illustration). Thus, there has never been a Ramadan total lunar
eclipse in December/January, nor April/May, nor in August/September.
(Eventually there will be, but not for many thousands of years) (2).
Dates of central solar eclipses occurring during Ramadan have
ranged from 12th November to 25th December, or from 20th March to 26th
April, or from 16th July to 22nd August (3): (as above, these are
Gregorian dates). Here, it is appropriate to include annular as well
as total eclipses provided they are "central" (i.e. lying on the lunar
umbral axis). The only difference with annular eclipses is that they
display a narrow ring of sunlight around the dark lunar disc - caused
by the moon being slightly further away from us, or by the sun being
closer to Earth than normal.
So why do Ramadan eclipses prefer certain dates? They appear to be
tuned to a near-synchronisation between three and a half revolutions
of the moon's orbital plane - and the 65-year period during which the
date of mid-Ramadan migrates twice round our solar calendar. The full
explanation for the "date-clustering" is complicated, involving
periodic readjustments caused by slow accumulation of the difference
between the cycle-lengths in that near-synchronisation (4).
Double Eclipses during Ramadan
----------------------------
Sometimes a Ramadan will contain a solar and a lunar eclipse. That
inevitably provokes comment, because of traditions that such a
"double-eclipse" is a portent for some unusual event. Ithna'asheri
Shi'ites, for example, believe that their Twelfth Imam will reappear
after a /Ramadan /double-eclipse (although those two phenomena will
supposedly take place in reverse order, with the solar one occurring
in mid-month (5); that will require the moon to suddenly double its
speed of movement after the onset of the Holy Month!)
In March/April 1894 (Ramadan 1311), Mirza Ghulam Ahmad (founder of
the Ahmadiyya or Qadiani movement in Pakistan) interpreted a double-
eclipse as a sign that he was a genuine modern-day prophet (6). The
lunar eclipse during that particular month was only partial, although
the solar one two weeks later was total in a few places in eastern
Asia (7). However, there was nothing at all extraordinary about those
two eclipses: every 22 or 23 Islamic years there is at least one
Ramadan featuring a pair of eclipses two weeks apart (8) - one of
which is usually partial; see Table 1.
Very much rarer is a Ramadan containing two otal eclipses. Table 2
lists all such occasions since AH 1, as well as during the next 200
years (9); (its solar eclipses are all central, with annular ones also
included).
It will be interesting to see whether the two total eclipses
scheduled to occur during Ramadan 1424 (AD November 2003) - are cited
to support a claim similar to that made by Mirza Ghulam Ahmad, or as
proof of the significance of some extraordinary event.
--------------------------------------
Table 1: Recent double-eclipse Ramadans
-------------------------------------
AH AD LUNAR SOLAR
.---- ---- ------- --------
1402 1982 T 6 Jul P 20 Jul
1401 1981 P 17 Jul CT 31 Jul
1379 1960 T 13 Mar P 27 Mar
1378 1959 P 24 Mar .CA 8 Apr
1357 1938 T 7 Nov P 21 Nov
1356 1937 P 18 Nov CA 2 Dec
1335 1917 T 4 Jul P 19 Jul
1334 1916 P 15 Jul CA 30 Jul
1312 1895 T 11 Mar P 26 Mar
1311 1894 P 21 Mar CA 6 Apr
1290 1873 T 4 Nov P 20 Nov
1289 1872 P 15 Nov C 30 Nov
1267 1851 P 13 Jul CT 28 Jul
1245 1830 T 9 Mar P 24 Mar
1244 1829 P 20 Mar CT 3 Apr
1223 1808 T 3 Nov P 18 Nov
1222 1807 P 15 Nov C 29 Nov
1200 1786 T 11 Jul CT 25 Jul
1178 1765 T 7 Mar P .21 Mar
1177 1764 P 18 Mar CA 1 Apr
1156 1743 T 2 Nov P 16 Nov
1155 1742 P 12 Nov CA 27 Nov
1133 1721 T 9 Jul P 24 Jul
1110 1699 P 15 Mar C 31 Mar
1089 1678 T 29 Oct P 14 Nov
1088 1677 P 9 Nov CT 24 Nov
1066 1656 T 6 Jul (T) 21 Jul
1044 1635 T 3 Mar P 18 Mar
1043 1634 P 14 Mar CT 29 Mar
1022 1613 T 28 Oct P 12 Nov
1021 1612 . . P 8 Nov C 22 Nov
999 1591 T 6 Jul P 20 Jul
998 1590 P 17 Jul CA 31 Jul
----------------------------------
Notes for Table 1
-----------------
Dates apply to the instant of maximum eclipse.*
Lunar eclipses: P=Partial; T=Total; Central lunar eclipses are
always total.
Solar eclipses: CA=Central and Annular; CT=Central and Total;
(T)=Total but non-central; P=Partial; C=Central, alternating
between Total and Annular.
-------------------------------------------
Table 2: Ramadans with two central eclipses
----------------------------------------- -
1st row - LUNAR, 2nd row - SOLAR
--------------------------------
AH AD DATE WHERE VISIBLE
---- ----- ------ -------------------------------------
283 896 .29 Oct Pacific & adjacentlandmasses (25 Pct)
12 Nov Canada; Alaska; NE Pacific (18 Nov)
305 918 5 Mar Eurasia; NE Africa(28 Feb)
20 Mar Antarctic; south.Indian Ocean (15 Mar)
462 1070 2 Jul Pacific & adjacent landmasses (26 Jun)
16 Jul Arctic; Siberia (10 Jul)
.529 1135 4 Jul America; Pacific; New Zealand (27 Jun)
19 Jul Antarctic; far south Pacific (12 Jul)
.596 1200 5 Jul Pacific & adjacent landmasses (28 Jun)
*19 Jul Siberia; Arctic; NW Atlantic (12 Jul)
1200 1786 11 Jul Pacific & adjacent landmasses
.25 Jul South Africa & adjacent oceans
1424 2003 9 Nov Europe; SW Asia; Africa; America
23 Nov Antarctic; south Indian Ocean
1580 2155 19 Mar Europe; Africa; America
. *2 Apr . .China; Russia; Kashmir; Mongolia; Afghanistan
------------------------------------------------------------------
Notes for Table 2
----------------
Central lunar eclipses are always total.
The central solar eclipses listed above are total unless
asterisked - in which case they are annular.
Dates apply to the instant of maximum eclipse.
Extrapolated Gregorian dates are given even on occasions when
the old Julian calendar was in operation;* *the corresponding Julian
date is then shown below in brackets.
------------------------------------
NOTES and REFERENCES
------------------
1. Bao-Lin Liu and A.D. Fiala, "Canon of Lunar Eclipses, 1500BC-
AD3000", 1992; Willmann-Bell Inc., Richmond, Virginia. *Or: *J. Meeus
and H. Mucke, "Canon of Lunar Eclipses, -2002 to 2526", 1983 (2nd
edition); Astronomical Office, Vienna. See also note 2.
*2*. Eclipses may also be examined with computer software such as
EclipseMaster, MoonTracker, SunTracker and AstroCalc; Zephyr Services,
Pittsburgh, Pennsylvania. To help with the preparation of Tables 1 and
2, AstroCalc was modified to print out celestial positions of the Sun
and Moon near each Ramadan (i.e. every 354.367 days). Occasions when
the mid-/Ramadan/ Full Moon or the /Eid/ New Moon were close to the
ecliptic plane could then be highlighted - demonstrating that this
occurs every 22 or 23 Islamic years.
*3*. Ibid. See also H. Mucke and J. Meeus, "Canon of Solar
Eclipses, -2003 to +2526", 1983; Astronomical Office, Vienna.
*4*. Letter from D.L. McNaughton to the "Journal of the British
Astronomical Association" volume 105 no. 4 (1995); (it has been
appended here).
*5*. Attributed to the Fifth Imam of the Shi'ites - Muhammed al-
Baqir ibn Ali ibn Husayn - who was describing events which would
precede the eventual appearance of the Mahdi. Narrated by Amar ibn
Shamir, quoting Jabir; see "Dar-e-Qatni" volume I, p. 188.
*6*. See Mirza Ghulam Ahmad, "Ruhani Khaza'in" volume 17, p. 132.
*7*. See notes 1, 2 and 3 above.
*8*. Ibid.
*9*. Ibid.
----------
Letter to the Journal of the British Astronomical Association 105/4,
1995 (From Dr David L. McNaughton)
Recently I was asked to examine occurrences of all lunar eclipses during
Ramadan since AD 622 (i.e. since the beginning of the Islamic era),
and an unexpected pattern emerged. I am trying to put together a
tentative explanation for the pattern, and would appreciate comments.
Every total lunar eclipse taking place during Ramadan has been
restricted to certain dates, comprising the three short intervals 22
February to 13 March, 20 June to 11 July and 16 October to 7 November.
(To maintain continuity, dates recorded in the old Julian calendar prior
to AD 1582 (or 1752) were converted to 'extrapolated' Gregorian-style
dates for this particular illustration).
So why do Ramadan eclipses prefer certain dates? They appear to be
tuned to a near-synchronisation between three and a half revolutions of
the moon's orbital plane - and the 65-year period during which the date
of mid-Ramadan migrates twice round our solar calendar. (Is that close
resonance purely accidental?)
Detailed eclipse calculations do actually reveal a very slow drift: e.g.
after AD 3000 those Ramadan eclipses will tend to move into late
March, late July and mid-November.
Ramadan total lunar eclipses may be grouped into three parallel
series. Each such progression comprises events 65 years and 2 days
apart (on average). That is of course virtually the same as 67 Islamic
years (804 lunations). (Furthermore, this time-span is just two hours
short of 872 draconic months). The three parallel series are
separated by phase differences of 21 or 22 years; at present they
comprise March, July and (mostly) November eclipses respectively.
Within each progression, the two extra days every 65 years do cause a
slow but steady date-shift which continues for a few centuries. However,
that gradually moves the eclipses away from the lunar nodal points, so
this date-shift cannot be maintained indefinitely. Eventually, the
progression is disrupted by a 'backward jump', which occurs after two
successive Ramadans witness a total lunar eclipse. The second member
of that pair then takes over as the starting point of a new series of
eclipses 65 years and 2 [days] apart, but containing dates displaced 11 days
earlier than those taking place in the first series. Thus, this
readjustment process interferes with and retards the tendency for
Ramadan eclipses to drift.
References and Software
---------------------
See notes 1 and 2 of the main paper above.
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