The idle ramblings of a Jack of some trades, Master of none

Jul 2, 2011

A Sphere in Religion

What are the religious consequences of a spherical Earth? They are manifold, and solutions provided have been as much driven by convenience as science.

Take the example of the Judaic Sabbath. Religious law mandates that no work be done on this day. How to determine which day is the Sabbath, however? For stationary people, there is no issue. What if one is a traveller, and circumnavigates the planet? As the Jewish encyclopedist David Gans realised and documented in the sixteenth century treatise Mogen Dovid, there would be a serious problem:
Suppose that Reuven, Shimon and Levi stand at a single point... Reuven sets out to the west and circles the world, Shimon circles to the east, and Levi remains in place... On one and the same day it will be three days after the Sabbath for Levi who remained, two days after the Sabbath for Reuven [who circled west, with the sun], and four days after the Sabbath for Shimon [who circled east, against the sun]. The difference between Reuven and Shimon will be found to be two days. 1
Impossible, then, for travellers to know the exact day of a religious festival. They could already feel the tongues of hell-fire touching their feet.

David Gans considered the issue serious enough to request the Holy Roman Emperor Rudolf to help, and the likes of Johannes Kepler got involved: "After they considered these questions for several days, and debated with me, they admitted and were not ashamed to say that they had not attained a correct and satisfactory answer."

The solution eventually was one of pragmatism and convenience: the Sabbath is what the local custom says it is.

Now, consider the problem of facing Mecca - the Qibla direction - when a Muslim wants to pray. The faithful not too far from Arabia had a pretty fair idea of the direction of the holy city. They knew that twice a year (on May 28 and July 16) the sun is directly overhead on Mecca at noon. So all they needed to do was to look at the direction of the sun at the local time corresponding to the Meccan noon, and orient their mosques thither. (I assume they knew how many hours Mecca was ahead or behind them.)

It turns out that the direction they gazed at was along a great circle, a geodesic, the shortest distance between them and Mecca.

Now imagine the situation of a Muslim in North America. A flat earth map would indicate that the Qibla is south-east. But the earth is round, and so the geodesic from North America to Mecca goes almost via the North Pole. The Muslim, in other words, has to face nearly north - quite counterintuitive.

Still, they found a solution - using the same methodology as their brethren did nearer to Mecca:
It has been observed that around noon time of Makkah, it is about 6 am in Nova Scotia, Canada and Maine, USA. The sun rises in those locations as it comes overhead Makkah at local noon time. Facing the sun on those two dates around 6 am gives the correct direction of Qibla from North America. Those who had observed this confirmed that they saw the sun in North East direction at the specified time and date. Therefore, it is correct to say that Qibla from North America is generally North-East, except from Alaska and California where it is close to North direction. 2

1. Paul Kriwaczek, Yiddish Civilisation: the Rise and Fall of a Forgotten Nation (London: Weidenfeld and Nicolson, 2005)
2. Qibla Direction.


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