WHAT'S MY QIBLA?
 --------------
 John Pazmino
 NYSkies Astronomy Inc
 nyskiesastronomy@earthlink.net
 2007 December 8
Introduction
 ----------
    The question comes to me from time to time, 'what is the qibla for 
New York?'. From somewhere I recall it is 59 degrees east of north. I 
knew also that the qibla is the direction toward Mecca along a great 
circle from the City and that Muslims face this direction for praying. 
    In July 2007 the question came again, with a twist. 'How is the 
qibla determined?' Knowing that it involves the 'straight line' from 
New York to Mecca, I figured it would be a simple task for spherical 
trigonometry and some formulae exercised on a calculette. 
    To a large degree this is true. But in poking around, I found 
there is more to the qibla question than that. 
Spelling 
 ------
    Before going further, I must note that in this here article the 
spelling of various Arabic words is, uh, scattered. Arabic has sounds 
and accents that do not map well into the Latin alphabet in a 
consistent manner. The effect is much like the attempts of European 
settlers to write down words from the native Americans. 
    More than that, among Arabs writing in the Latin alphabet, like on 
websites or magazines, the spelling of a given word can differ widely. 
The situation is like, but more severe than, the variant spelling of 
the Arabic names of stars. 
    For the word 'qibla' I found 'qibllah', 'quiblla', 'kiblih', 
'quabbla', to recall only a few of the ways this word turned up in the 
litterature I examined. 
    Hence than that, because I have no expertise in Arabic as a 
language and I took material from many separate sources, the speeling 
of Arabic words here is not even within a particular scheme of 
translitteration. 
    Please expect the spellings to be at variance with what you may be 
used to elsewhere. Perhaps some reader versed in reanslitterated 
Arabic can furnish a consistent suite of spellings for the next 
revision of this article?       
What is qibla? 
 ------------
    From history and culture, Muslims kneel and face Mecca when they 
pray. Mecca, in present-day Saudi Arabia, is the birthplace of Islam. 
More specificly, they face the Kaabah, or central ark, in the 
courtyard of the main mosque of Mecca. This ark, of wood and stone, 
rebuilt over the centuries, is today roughly a cube about 12 meters on 
a side. From what I read about the Kaabah, the interior is a n emtpy 
chamber with no artificial lighting and decorated with Arabic 
scirptures. Only the keepers of the ark are allowed inside. 
    On the outer wall at eye level is a silver display window framing 
a dark stone. This is likely a meteorite that was found in or near 
Mecca in the preIslamic era. While it is not itself a sanctified 
object, it enjoys a special honor for Muslims. 
    When Islam was still young and its followers lived in or near 
Mecca, it was easy to face the Kaabah or, at least, the mosque itself 
from anywhere within its sight. The practice showed the unity of 
Muslims and not a glorification of the Kaabah or the meteorite. During 
praying, Muslims deploy in circles centered on the Kaabah. 
    As people farther away took up the faith, they were more likely to 
live beyond sight of Mecca. A way was needed to tell where Mecca was, 
so the prayer could face in the proper direction. 
    For short distances away, within a couple hundred kilometers, a 
straight line on a flat map, like a modern road map, was valid. The 
flat map was small enough to be a good approximation to the curved 
Earth surface, such as that of a US state or European province. 
    Beuond that, things got tricky.
Qibla in English
 --------------
    'Qibla' is now a word in English meaning ' orientation','focus', 
'heading', 'bearings'. It's used both in the literal sense of getting 
about on travels and in general life. One of the earliest mentions I 
heard was in the mid 1970s at a cafeteria. You stopped at various 
counters to assemble your meal. One fellow, in a group of coworkers, 
was turning round left and right in place looking for a certain 
counter. A buddy shouted,'Yo, Pete, you lost your qibla?'. 
    Similar sense is applied to a person choosing or shifting among 
careers, investments, lifestyles, relationships. 
    'Mecca' is also an English word, almost always spwlling 'Mecca' or 
'Mekka'. It means a focal place where large crowds are attracted from 
time to time for some common purpose. It could be a park or square, a 
stadium or pavilion, or a whole town. The purpose has to be a special 
one, occurring at longish intervals, annually typicly. Examples are a 
carnival, festival, convention. It can't be an ongoing function like 
that of a train depot or maarket place. 
Why face Mecca? 
 -------------
    There is no compelling reason to do so, except as a deep tradition 
to show the overall unity of Muslims thruout the world. A Muslim 
should make a good faith effort to face Mecca to pray using what ever 
resources he has to hand. With Islam represented in just about all 
countries by the early 21st century, there is usually an Islamic 
authority close by who informs about the local qibla. 
    On travels or in strange territory, it may be tough to figure out 
where Mecca is. There are also situation where the Muslim can not turn 
toward Mecca, like being in an airline seat or minding a control 
console. In such cases, the Muslim enjoys a waiver. 
    There are situations where the Muslim is in rapid change of 
heading that would force him to continuously change his orienttion to 
keep Mecca in front. The modern example is an Muslim astronaur in 
Earth orbit. In such cases, he should try to face mecca at the start 
of his praying, then stay put until he finishes, letting Mecca slew 
away from his local forward position. 
    The underlying principle is that the praying is given to the 
creator, not to a earthly thing like the Kaabah. Hence, the creator, 
who is every where and every when, will receive the devotions of the 
Muslim regardless of orientation. Facing Mecca to pray is only a 
cultural tradition that shold be followed when pracitcal but which can 
be waivd for special circumstances. 
Qibla accuracy 
 ------------
    Because it is impossible to face exactly toward Mecca, but only to 
within a degree or so, excessive accuracy in the computation of qubla 
is empty accuracy. For just about all purposes, a qibla cited to the 
nearest whole degree is perfectly valid. 
    The qibla for New York City is variosly stated in the range of 58 
to 59 degrees. This is quite adequate for a proper facing toward Mecca 
from any where within a few tens of kilometers around Manhattan. 
    Ideally, a mosque's axis should align with the qibla. In many 
situations the mosque is built into an existing structure where such 
alignment is impossible. As a means of orienting the congregation, a 
marker is placed on the wall behind the prayer master. The 
congregation faces that marker and, thus, faces Mecca. 
    In New York, the first allnew mosque, not fitted into older 
structure, is the Islamic Cultural Center on 96th St and 3rd Av on 
Manhattan. The Center is oriented to Mecca, explaining its skewed 
placement on the block relative to the street grid. All previous 
mosques were built into existing buildings with no alignment to Mecca. 
Which qibla?
 ----------
    The one, alnost universal, facing of Muslims in praying is toward 
Mecca. However, there are niche groups of Nuslims who face other 
special towns. I came across Cairo, Jerusalem, Constantinopolis, and 
Alexandria (in Egypt) as a focal point for praying. The concept of 
qibla is the same for all, so I'll stay with that for Mecca. 
Moslem science 
 ------------ 
    Because of the need to facilitate remote Muslims to face Mecca, 
early Islamic leaders used science to figure out the qibla for various 
places on Earth. For starts, they, as did other educated people, knew 
the Earth is substantially a sphere. The school-boy story about 
sailors fearing to fall off the 'edge of a flat world' is, and always 
was, nonsense. 
    The deck hands, recruited from riff-raff hanging out on the docks, 
may have held such dread from the prevalent shallow education among 
the general public. The ones who commanded the ships, ran the 
businesses, funded the trips, and otherwise made the world go round, 
were in full knowledge of a round Earth. 
    As a matter of fact, in the late mediaeval times, when Europe 
started to revive from the Dark Ages, they drew heavily on Islamic 
scholars for skills and arts of navigation. Columbus himself, as 
example, either spoke Arabic or had an aide who did, so he could 
discuss astronomy and navigation with Islamic colleagues. Some papers 
attributed to him have Arabic notations, but it is still not certain 
whether Columbus or an associaite wrote them. 
Europe's gratitude 
 ---------------- 
    The gratitude of Europe to Islamic science of the late mediaeval 
years and into the renaissance is forever immortalized in the names of 
craters on the Moon. They were placed there by European astronomers in 
the 1600s to thank Arabian figures who contributed to the progress -- 
some claim sheer survival! -- of western culture thru the Middle Ages. 
    This gratitude continued to the late 20th century when the Moon's 
averted hemisphere was charted by spacecraft. A similar thank-you for 
Arabic science now extends to craters on certain other planets and 
their satellites. 
    Islamic astronomers also, as just one example, sussed out the size 
of the Earth as about 40,000 kilometer circumference. Columbus, for 
what ever reason, disputed this value and stayed with an earlier one 
of only 25,000 kilometers. 
    In his day this trip, allowing for the land mass of Europe and 
Asia, would be across an ocean narrow enough for the ships of the late 
1400s to survive out of reach of land. If the world was bigger, the 
Arabian size, that ocean would be far and away too wide for a 1400s 
ship to last. The journey would be a one-way ticket to Davy Jones 
locker. No one seriously entertained the possibilty of a new 
intervening land that interrupted this huge ocean. 
    Various Islamic explorers described large regions of land, most 
likely Brazil, beyond the Canary and Azore islands. Some Arabian mural 
maps in Spain have 'Plus ultra' noted in the waters west of Europe! 
    It just so happened that when Columbus expected to arrive near 
China, after traverseing his short ocean, he did hit islands like those 
in southeast Asia. These were the 'Indies' whence today we have the 
East Indies, the real ones in Asia, and the West Indies, the ones in 
the Caribbean Sea. 
    It wasn't until his later trips that he realized he found a whole 
other continent separting the ocena into two, the Atlantic and the 
Pacific. That's why the East Indies are far WEST of the United States, 
while the West Indies are a bit EAST [and south] of it. 
Great circle
 ----------
    On a plane the shortest distance between two points is along a 
straight line between the points. The direction from the one to the 
other is the azimuth of that line. The azimuth from the other to the 
one is the ampliment, adding to the first azimuth for 360 degrees. 
    On a sphere this concept transforms into a great circle between 
the two points. If you put a plane thru the center of the sphere and 
turn it to touch the two points on the surface, it intersects the 
surface in a 'straight line'. This is the great circle connecting the 
two points. 
    The azimuths at the two ends are NOT ampliments! You must 
calculate each separately. Thus, it is essential to note from which 
point the azimuth is cited.
    If one point is at a pole of the globe, the great circles from it 
to all other points are meridians. The azimuth of any one is 180 
degree! From the remote point to the pole, it's 0 degree. 
    Mecca is no where near a pole of the Earth, so the calculation of 
qibla, or, what is really the same thing, of the great circle route 
requires formulae of spherical geometry. 
    In fact, because the lat-lon grid is somewhat arbitrarily defined, 
we can translate it so Mecca is at the pole. This is done in map 
projections where the point in the center of the map is the pole of 
the coordinate grid defining that projection. 
Great circle for New York
 ----------------------- 
    In this worked example I use a nominal geographic location for the 
City of 40.7 degree N lat and 73.9 deg W lon. New York City covers an 
area about 50 kilometers across, about 30 minutes of arc. Because we 
are so far from Mecca, some 10,300 kilometers, the qibla for this 
location is valid for about 100 kilometers around.
    I inspected qibla tables, worked out to the hundredth of a 
degree for Manhattan (unspecified place), then Hoboken, Yonkers, St 
George, Jamaica, Mineola, and other nearby towns. It is humanly 
impossible to distinguish in a praying posture between these qiblas! 
    In the maths below, phi is latitude; lambda, longitude; zeta, 
azimuth. The formulae are written as BASIC code, in a linear style. No 
attempt is made to replicate the actual maths symbols in this plain-
text article. 
    The maths are those of a spherical triangle with corners M for 
Mecca; C, the City; P, north pole. The qibla is angle PCM, in the 
normal sense of azimuth in astronomy or navigation. the distance 
between Mecca and New York is side CM. 
    Due to the erstaz way caculette handle trigonometry, you MUST mind 
the sense of the calculated angles and be ready to throw them into 
their complement, supplement, ampliment. A sketch, clumsily drawn 
here, helps keep things right way round. The curved sides CM and PM 
remind that the triangle is drawn on the Earth, NOT on a plane. 
                        P--------
                        |          \ 
                        |             \ 
                        |                \ 
                        |                  \ 
                        |      - - -         \ 
                        |   /         \       | 
                        | /              \    | 
                        |/                 \  | 
                        C                   \ | 
                                             \| 
                                              M 
 
    The formula for the angle at C, PCM, in angular measure, is 
    PCM = atn(sin CPM / ((sin CP / tan PM) - (cos CP * cos CPM))) 
    CP is the colatitude of New York, (90) - (+40.7) = 49.3 
    PM is the colatitude of Mecca = (90) - (+21.4) = 68.6 
    CPM is the delta(lon) between New York and Mecca, minding that the 
two are on opposite sides of the zero meridian. It is given a positive 
signum, regardless of which way you do the substraction. P = (-73.9) - 
(+39.8) = -113.7 -> +113.7. 
    The formula becomes 
    PCM = atn(sin 113.7 
      / ((sin 49.3 / tan 68.6) - (cos 49.3 * cos 113.7)))  
    PCM = atn(0.9157 / ((0.7581 / 2.5512) - (0.6521 * -0.4019))) 
    OCM = atn(1.637) 
    PCM = 58.59 
    Thus, the azimuth FROM C (New York) TO M (Mecca), PCM is 58.59 
degree. In THIS PECULIAR CASE, no adjustment for ampliment, 
complement, supplement is needed. The angle ALREADY, as seen in the 
sketch the right way round for the specification of azimuth. That is, 
azimuth is measured clockwise from north, thru east, back to north.  
    This angle, 58ish degree, is the very qibla of Mecca for New York. 
It is routinely rounded to 58, 58-1/2, or 59 degrees, all with utterly 
equal validity. 
Mecca to New York 
 --------------- 
    If, for some reason, you wanted the qibla of New York as seen from 
Mecca, you have to swop the colatitudes in the above formula. Note 
that the answer is NOT the amplument of 58.58, like it would be on a 
flat map. 
    PMC = atn(sin CPM / ((sin PM / tan CP) - (cos PM * cos CPM))) 
    OMC = atn(0.9157 / ((0.9311 / 1.1626) - (0.3649 * -0.4019))) 
    PMC = 0.9664 
    PMC = 44.02 -> 315.98 
    Notice that in THIS PECULIAR CASE the angle has to throw to its 
ampliment. That's because the calcked angle is the one INSIDE the 
triangle and falls to the LEFT, WEST, of the meridian of Mecca, side 
PM. Since azimuth is counted eastward from north, we must go round 
OUTSIDE the triangle, subtracting the 44ish degree from 360, to get 
the correct qibla. 
Shape of Earth 
 ------------
    For just about all domestic and most specialized purposes, it is 
well to treat the Earth as a perfect sphere. All celestial navigation 
and all spherical astronomy are founded on a spherical Earth. The 
geometry of a sphere is simple and yields results that are a whisker's 
distance from the vastly more complex maths of the real Earth shape. 
    Earth in a second order approximation is an oblate shperoid with 
the equator bulged out slightly. The equatorial diameter of Earth is 
about 25 kilometers more than the polar, a generally negligible amount 
against the 6,400 kilometer overall diameter. 
    In calculating qibla by the great circle method, the spherical 
Earth is assumed unless otherwise deliberately stipulated. For New 
York's qibla the difference between the qibla from the spherical and 
ellipsoidal glibe is only aabout a tenth of a degree. 
Qibla by the Sun 
 -------------- 
    It's one thing to work out the qibla and hand out the answer, but 
where is this azimuth in the landscape? A prayer has to face towad a 
local feature, beyond which, along the great circle, is Mecca. There 
ae two main ways to instruct the prayer about his qibla, the Sun 
method and qibla compass. 
    Imagine that you are a few kilometers from the Kaabah and can not 
see it directly. If at the Kaabah there was a tall mast with a lamp on 
top, you could find the Kaabah beyond the forground skyline and face 
toward it. If you were farther away, a taller mast could be built. 
    Beyond 50 or so kilometer, the limits of building masts, or even 
substantial skyscrapers, visible from that far away are too great. The 
late World Trade Center, among the tallest structures ever built, was 
visible from the Carskills, Taconics, and inner Poconos. But no human 
edifice could mark the Kaabah for a prayer even a couple hundred 
kilometers from it. 
    There is a very, very!, tall 'lamp' that can mark the location of 
Mecca. It's the Sun! With Mecca being at 21.4 degree north latitude, 
the Sun crosses the latitude of Mecca twice a year on its way to and 
from the summer solstice. On these two particular days, there is an 
hour when the Sun stands in the very zenith directly above the Kaabah. 
    The zenithal stations of the Sun over Mecca occurs on May 28 09:18 
UT and July 15 09:27 UT. You must convert UT to the local mean time of 
your location, including the offset from the standard timezone 
meridian. 
    Mind, too, the offset during your daylight savings time. In the 
United States daylight savings time prevails on both dates. You must 
be wisely about the practice in other countries where you fix the 
qibla by the zenithal station method. 
    If you on these dates and hours look toward the Sun, and note 
where it stands above your local skyline, you are looking toward 
Mecca. You got the qibla for Mecca once and for all. A photograph of 
the landscape with the Sun in it wil guide you for all the days 
therafter. It's a bit of luck that you have two shots at ths each year 
in case of bad weather. 
    Fortunately, there is a wiggle room of two days and about 8 
minutes. A cloud over Sun at the very moment that passes away in a 
couple minutes will not upset your qibla sighting. Nor will rain that 
clears up on the next day. 
    This trick works so long as you actually can see the Sun. The Sun 
illuminates half of the Earth, out to quite 10,000 kilometers from the 
subsolar point at Mecca. The other half of Earth, bwyond 10,000 
kilometers, can not see the Sun. It is down at the two critical 
moments. New York, at 10,300 kilometers from Mecca, misses the Sun on 
the two qibla moments because they occur before local sunrise. 
Qibla by the antiSun
 ------------------
    For those in the night side of Earth on the two qibla moments, 
there is the antiSun method. Wait until the Sun stands directly over 
the diametricly opposite point on the globe from Mecca. This is the 
antipode of Mecca, same latitude in southern hemisphere and 180 degree 
away in longitude. This point is in the South Pacific Ocean near no 
major island. 
    On these two other qibla moments, look straight at your shadow. It 
points into the horizon toward Mecca. A photograph of the landscape 
with that shadow fixes your qibla. 
    The antisolar zenithal crossing or, perhaps simpler to visualize, 
the solar nadir crossing of Mecca happen on November 29 21:09 UT and 
January 14 21:30 UT. 
    In New York, these translate to:
    November 29 16:13 LMT, Sun alt 2.6, Sun azm 238.6, qibla 58.6 
    January 14 16:34 LMT,  Sun alt 2.9, Sun azm 238.8, aibls 58.8 
    By utter chance, and ONLY that, the two pairs of dates are close 
to the dates of the Manhatan Stonehange sunset in summer and Manhattan 
Stonehenge sunrise in winter! 
An other solar method 
 -------------------
    The zenithal, or nadir, crossing method works as long as the 
weather is favorable on the two dates. If you miss the Sun due to 
clouds in a given year, you must wait a whole year for the next 
chance. To avoid such lengthly deadtime, an other solar method was 
devised. 
    In most places, the Sun at some hour of a good part of the year 
stands in the azimuth toward Mecca, but not actually over the very 
Kaabah. It's the direction that you're figuring out, so the Sun may be 
anywhere along the great circle from you to Mecca. There are periods 
of the year when the Sun never attains to the proper azimuth, but 
there the span when it does give you many shots at getting a good 
qibla fix. 
    For New York the Sun can touch the qibla azimuth of 59 degrees 
(rounded), only just after sunrise between June 11th and July 1st. 
That is, on the 20 days centered on the summer solstice. Then after 
during the day the Sun migrates right of the qibla. 
    This narrow window of qibla azimuth for the Sun results from the 
City's close proximity to the 'equator' of the world, whose pole is at 
Mecca. We're only 300 kilometers beyond that equator in the opposite 
hemisphere. Never the less, it does give a chance over a 20 day span 
to get a qibla fix instad of just the two days (even with a two day 
leeway) from the zenith/nadir method. 
Qibla by stars
 ------------
    Various bright stars stand in the azimuth of qibla at some time in 
their diurnal and annual motion. They offer many more days, to beat 
adverse weather, for finding your qibla. Once determined, by noting 
where the star stands over the local landscape, the qibla is fixed 
then after. 
    The star method is not widely promoted beecause it requires a 
familiarity with the constellations, an art rare among the general 
public. However, as examples here are the days and hours for Capella 
and Vega for New York. Times are EST, not EDST. 
  ----------------------------------------------------------------
  star    | 18h  | 19h  | 20h  | 21h  | 22h  | 23h  | 00h  | 01h  
  --------+------+------+------+------+------+------+------+------ 
  Capella |Dec 26|Dec 11|Nov 26|Nov 11|Oct 27|Oct 11|Sep 27|Sep 11
  Vega    |  --  |  --  |May*28|May 13|Apr 28|Apr 13|Mar 29|Mar 14
  -----------------------------------------------------------------
    I calcked the times for hours when a person would plausibly step 
outside and look for Vega or Capwlla. You may fix your qibla by this 
table within two days of the listed date and within 8 minutes of the 
listed hour.
    For intermediate dates and hours, you may linearly interpolate 
between the tabulated values. The result will be within the tolerance 
for a valid qibla fix. 
    These values will drift secularly due to precession, but are good 
for a single lifetime. Note that either one or the other is at the 
qibla, they being more or less opposite each other across the north 
celestial pole. 
    May 28 has a '*' to indicate that Vega is then is evening twilight 
at 20h EST. Vega is among the brightest stars in the sky. so it may be 
visible thru twilight. A '--' means the hour is in daylight before or 
near sunset; Vega would be quite invisible then. 
Celeestial navigation 
 -------------------
    The use of the Sun's or star's location in the sky to find a 
direction is a variation of celestial navigation. In celestial 
navigation we use their position to calculate our location on the 
Earth. It uses the direction to the Sun/star as an intermediate step 
in that process. 
    In brief, we first compute the altitude and azimuth of the 
Sun/star for the local hour of observation and for an assumed 
location. This location comes from general navigation skills and is 
the 'dead reckoning' position. 
    At the given hour we examine the target with the sextant, an 
instrument for taking altitude sightings. If the reading is greater 
than the computed altitude, we are closer to the target, on the 
spherical surface of Earth, than we assumed. If lesser, farther. 
    On a map we mark our dead reckoning place and draw a line from it 
into the azimuth of the target. If the assumed altitude is too small, 
we pace off along the azimuth line the deficit minutes of arc -- which 
are the same as mautical miles (about 1,800 meters) -- TOWARD the 
target. The derviced point is where we really are. 
    If the assumed altitude is too big, we pace off the sufficit 
minutes of arc AWAY from the target along the azimuth line.  The final 
place we land at is where we actually are.
    We pick at least two stars so we get an intercept of lines on the 
chart as a check against each other. To get a better intercept, we 
choose stars about 90 degree apart in azimuth. 
    The altitude sighting of stars is done in evening or morning 
twilight. We need both the star and the horison to see thru the 
sextant. This period of time, where both the brighter stars, used in 
navigation, and the horizon are visible is nautical twilight. 
Qibla compass
 -----------
    A handy device for Muslims who travel is a qibla compass. This may 
be either a physical device or a computer program on a handheld. In 
the physical form it is a regular camping/hiking magnetic compass set 
into a well marked in what at first look like degrees of azimuth. The 
aero point is a stylized minnaret, altho it may look more like a 
stylized arrow. 
    In the models I saw, the well is divided with 400 -- not 360! -- 
parts. They are NOT degrees of azimuth. I could not learn why this is 
so, but in the end it really doesn't matter. On the smaller model, for 
the pocket, there are 40 divisions, each corresponding to 10 on the 
large models.
    From the local Islamic community or a booklet with the device you 
get an index number fo the qibla. Place the comapss on the ground 
where you are kneeling on to pray. Turn the entire gadget so the north 
end of the compass needle points at the index number. The zero point 
(arrow or minnaret) now aims to Mecca. 
    The index number is in substance the ampliment of the qibla, plus 
the magnetic deviation from true north. For New York on a 400-part 
compass, the index number is 320. This can be derived by 
    (geographic qibla) - (magnetic deviation) = (magnetic qibla) 
    (59)               - (-13)                = 72 
    (mag qibla) - (360) = (amplument of mag qibla) 
    (72)        - (360) = 288 
    (ampl mag qibla) * (400/360 ratio) = (index number) 
    (288)            * (10/9)          = 320 
    One thing I was surprised at is the large deviation of magnetic 
north, 13 degrees west of geographic north! It turns out that the 
magnetic pole wanders rapidly up there in north Canada. The net motion 
as seen from New York is westward, away from the geographic north, by 
about a degree per decade. This is important in navigation by magnetic 
compass. You better update old navigation charts and tables. 
    The index number, of the ones I looked up on various Moslem 
websites, all seem to assume the 400-part compass. It may be well to 
specificly ask if the offered index number is for a 400 or a 360 part 
compass, just to be safe. 
    If the number is for the opposite dialing from that of your 
compass, ratio it by 9/10 (400 index to 360 dial) or 10/9 (360 index 
to 400 dial). 
    An other wrinkle is that the index number may be cited for a 40-
part (or 36-part) compass. In this case, suffix a zero (multiply by 
10). Or divied by 10 if you got the 40-part compass and are offered a 
400-part index number. 
    This can be misleading for a low index number. It could be in 
units or in truncated tens. '25' may be 25 or 250. Ask which it is! 
Here's China
 ----------
    It seems that more and more articles of everyday life are imported 
from China. Most of the goods are passably good and are a fair value 
for the price. You don't feel too bad if the shoulder bag seams burst 
on you; you only paid $5 for the bag. 
    When looking for qibla compasses to inspect, I found many are made 
in China! And they are cheap, in the $7-$25 range. This is often LESS 
than what the magnetic compass by itself costs as an American product! 
    What's more, the construction seems adquate for gentle handling, 
like packing in carryon luggage. The factory just glues the magnetic 
compass into its well, sometimes in some symmetrical way. The well is 
molded with the 40/400 or 36/360 divisions around it in both 'arabic' 
and real Arabic numerals. 
    That's it, really. There is no blessing, benediction, holy water 
sprinkle, or other ritual to be done. It's ready for use straight from 
the box.
    The only down side could be the instruction book. It may be in 
pigeon English, or pigeon Arabic!, and could have grammar, spelling, 
printing mistakes. You can discard the book and use the index numbers 
from a local Islamic source. 
Possible worry
 ------------
    With the concern in 2007 about lead paint on toys and poisoned pet 
food from China, it's best to exert consumer smarts when shopping for 
a qibla compass. This is specially the case if the compass is given to 
a child entering the culture. The device could be expropriated as a 
handy teething ring! It can also happen that lax workmanship leaves 
flashing or burrs on the compass that can break off and be swallowed. 
Ask at the local health or consumer agency about the safety of a 
compass under considertion. 
Computer compass
 --------------
    A handy computer program for a handheld is a qibla compass. Even 
if you're not a Muslim, it can be a useful general purpose compass for 
all outdoor activiry by day. After setting your home location and 
switching daylight time on/off, the screen shows a compass rose, a 
qibla mark, and a Sun symbol. It self sets from the handheld's clock. 
    I heard of a qibla program that includes the Moon for use after 
sunset or before sunrise but I could not find it to try out. 
    Hold the computer screen horizontal and turn it so the Sun symbol 
aims at the Sun in the sky. You may hold a pencil upright on the 
symbol and turn the computer so its shadow fall over the center of the 
compass rose. 
    The compass is now aligned to the geographic directions and the 
qibla mark points to Mecca. It really works. Ignoring the qibla mark 
leaves a good computer compass for hiking, camping, and the like. 
    In the specific program I have, the Sun is displayed for ANY hour 
of the day, even at night. Checking with astronomy programss, the 
Sun's direction is correct, only it's out of sight below the horizon. 
Craig's reverse-azimuth map 
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    You can NOT use an azimuth map centered on Mecca, like for airline 
routes, to find your qibla. The azimuth labels are those FROM Mecca to 
rest-of-world. As we saw for New York, as example, the qibla from 
Mecca to ROW is NOT simply the ampliment of that from ROW to Mecca. 
    For a rough qibla fix there is the reverse-azimuth map, also 
called the 'Mecca map'. This is a world map, centered on Mecca, 
invented by Craig in 1910. The longitude meridians are parallel 
verticals. The latitude circles are twisted out of their 90-degree 
intercept with the meridians. 
    I'm being kind to say that the shapes and sizes of the countries 
are wildly distorted. The map, when extended to cover the whole globe 
reesembles a bowtie with a large knot! 
    Radial curves from Mecca, in the center, are lines of constant 
azimuth TO Mecca. They are labeled NOT with the azimuth seen at Mecca, 
but with that seen from points along the curves. That is, the azimuths 
are 'reversed'. 
    The world is contorted to make all points with a given qibla sit 
on the corresponding radial line. Finding your location in this 
geography can be a bit of a hunt. 
Other 'Mecca' maps 
 ----------------
    Hammer in 1910 improved Craig's map by building in both reverse 
azimuth and distance from Mecca. When covering the globe, the thing 
looks like a cookie with an excentric C-shape hole! A line from any 
point to Mecca in the center gives both its qibla and distance from 
Mexxa. As you may expect, the countries are wildly contorted out of 
shape and size. 
    It turns out that there can be TWO places on Earth with the SAME 
qibla AND same distance from Mecca. Hence, the Hammer map, and the 
next one from Tobler, have regions where countires OVERLAP! They share 
common points of azimuth and separation from Mecca. Need less to say, 
finding your location within these zones can be tricky. 
    Tobler in 2002 invented a qibla map that is at least simple to 
use, while being as crazy in form as the others. He plots qibla 
against distance as a simple graph. Distance is the x-axis; qibla, y-
axis. Mecca is the whole top edge of the map with qibla ranging from 0 
(left side) to 360 (right side). 
    Distance from Mecca is zero at the top to 20,000Km (half the Earth 
circumference) at the bottom. The antipode of Mecca, in the Pacific 
Ocean, is along the bottom edge. 
    What happens within the graph is an other story. There are zones 
of overlap where two distinct places share the same qibla and distance 
from Mecca. While the overall shape is rectangular, there is in the 
middle an elongated hole. The map looks like the cover plate for a 
light switch! Or the top of a box of popup tissue! 
    A steroegraohic map centered on Mecca with the normal lat-lon grid 
is yet an other aid for finding qibla. A stereographic map preseves 
angles and all great cirles are true crcles or straight lines. A 
radial line from Mecca cuts your site's longitude meridian at the 
correct angle for qibla. 
    You do have to measure this angle by geometric construction and an 
angle gauge. For a portion of this map covering a single country, this 
may be feasible because the lat-lon lines can be farther apart and 
easier to read. 
Early maps
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    The routine way to issue qibla information in the Islamic lands 
was by tables and math books. These are preserved from the earliest 
era of Islam. Until 1989 we had no actual maps from early Islam. 
    In that year a brass qibla map was discovered in Iran. It isThe 
engraved on a disc about 24cm diameter and is fitted with a ruler 
pivoted at the center over Mecca. A second specimen was found in 1995. 
    From books already in hand about this device, the 1989 sepcimen 
lacks a detachable sundial and embedded magnetic compass. The 1995 one 
is complete. The compass orients the map so the qibla on it aims to 
Mecca. The sundial seems to be just for finding the hour of the day, 
perhaps for times of praying. 
    They date from around 1700 and are remarkably similar to the 
central part of the Hammer map! With the sundial and compass, It's the 
earlier-day version of the computer compass I described above! 
    They cover the region around Mecca, most of Europe and some of 
Africa. This was more or less the full diffusion of Islam in the 17th 
century, Countries, coasts, rivers are not laid out, just towns as 
labeled dots. By placing the ruler over your town, the qibla is read 
from the rim. Distance is taken from the scale on the ruler. 
    Scholars examining these instruments conclude that they are 
accurate and correct, save for flaws in geography. Geography in the 
western world in the 17th century was also a much fragmented art. 
Flat-earth method 
 ---------------
    While collecting material for this article I came across a really, 
like really, bizarre feature of American Moslem practice. It seems 
that some minor groups in the United States do not use the great 
circle method to find qibla. They go by -- I am NOT making this up!! -
- a flat-earth model. No, these folk are not sputniks of the flat-
earth belief, but they would make a capital poster child for it. 
    In this scheme of qibla, the world is a flat plane on the Mercator 
projection. The Mercator map has the property, useful in the dawn days 
of European sailing, that a stright line between two points has a 
constant compass bearing along it. A sailor leaving one end would 
merely have to keep this bearing and he will get to the opposite end. 
This line is a 'rhumb line'. 
    The idea works only on paper -- litterally -- because there are so 
many obstructions, not the least of which is intervening land along 
the rhumb line. However, when ocean sailing was a new pursuit in 
Europe in the late MIddle Ages, the Mercator method was about the best 
chance of getting from place to place on the high seas. 
    The rhumb line is not the shortest distance between the end 
points. It is not even a 'straight line'. It is a spiral that 
eventually joins the two poles of the world. On the Mercator map they 
appear straight because the map is on purpose distorted at the poles 
to make the longitude meridians stay parallel and to spread out the 
latitude circles. This causes the famous 'Greenland effect', where 
Greenland, a modest island near the north pole, looks as big as South 
America. 
    From the pragmatic view of the 1400s navigator, the shortest 
distance was not all that critical. The trip acorss the sea would take 
a couple months at least, anyway. Having to be at sea an extra couple 
weeks because he followed a rhumb line, not a great circle, didn't 
matter that much. 
    The result of using the rhumb line in the US for qibla is just 
ludicrous. It aims the prayer into an azimuth for New York of about 
110 degrees rather than the correct 59 degrees! The argument is that 
on the flat map the direction from New York to Mecca IS kind of east-
southeast. It's NOT way up to the northeast on the great circle. 
This doesn't work 
 --------------- 
    The rationale offered in the litterature I read is plain nonsense. 
It is trivial to show that the rhunb line doesn't work. For starts, 
the Mercator map used is always sliced open from its real cylinder 
shape at or near the International Date Line. On this map the line 
between New York and Mecca does steer an east-southeast course. 
    The slicing of the map near the IDL is merely for convenience. It 
keeps the parts of the workd important in western history connected 
near the middle of the map. The Atlantic Ocean, critical in western 
history, is in one piece. Voyages are easier to follow across it 
between Europe and the Americas. 
    However, pura mente BECAUSE the Mercator map is a cylinder, it may 
be unrolled along ANY meridian. Suppose we cut it along the 0th degree 
meridian. This splits Europe and Africa into the two sides of the map, 
but keeps the Pacific Ocean together. This map could be useful in 
Hawaii, Japan, Australia. 
    Now the 'straight line' from New York to Mecca is a little south 
of west! It runs across the whole United States, Pacific Ocean, the 
Far East, India, the Middle East. Isn't THIS the 'correct' rhumb line? 
    In fact, as a cylinder, the Mercator projection has TWO rhunb 
lines connecting any two points on it! One spirals clockwise toward 
the poles; the other, counterclockwise. By applying the reasoning of 
the flat-earth Muslims, each is just as valid as the other. At their 
praying session. some of the congregation should be allowed to face 
east-southeast and the rest to face west-southwest! 
    An other way to demolish the flat-earth argument is to rotate the 
lat-lon grid so Mecca is at one pole. Can any one fail to see that the 
direction to Mecca is along a meridian from any place on the globe? 
Meridians are great circles, not rhumb lines. 
Why a flat-earth?
 --------------- 
    I heard assorted, equally silly, motivations for setting aside the 
traditional and proper methods of finding qibla. Here I note only two 
extreme explanations. The first is that American Muslims want to 
distance themselfs from the overseas Muslims. They seek to avoid being 
gathered up with the fundmentalists and radical elements of Islam and 
be treated as a distinct American group. 
    Facing Mecca is one highly visible trait of Muslims, one that is 
commonly mocked by those beyond the Moslem culture. Hence, by 
modifying this feature, American Muslims hope to segregate themselfs. 
'See, we don't katow-katow to those people. we have our own way to 
face Mecca. We be the nice guys.' 
    The other extreme is that the flat-earth feature is part of the 
radical agenda to dismantle knowledge, understanding, learning in 
America. By teaching a nonsensical theme, they can say, 'Look, western 
science is wrong. It shows we face northeast to Mecca. We really have 
to face east-southeast!'. This platform is on a par with the 
biblicists in other sectors of American society. They hope to impose 
bogus biology and cosmology, replacing science and objective study of 
these subjects. 
    I can't assess what the true story is, but you will hear them and 
many others across the social and political spectrum in the years to  
come. So far, the falt-earth Muslims are a fringe sector among the 
tens of millions of traditional Muslims in the United States. 
Conclusion
 -------- 
    The practice of facing Mecca when out of its sight and in 
strange territory was a prime factor in the development of science, 
notably astronomy and mathematics, in the early Islamic period. This 
work was deeply appreciated by western peoples, who then were 
struggling out of the Dark Ages. Today, finding qibla is a trivial 
matter of pressing buttons on a computer or lining up a magnetic 
compass. yet it still reminds us of the time and energy it took to get 
the maths and science in place over a millennium ago.