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It's a puzzlement!

Something I've never heard anyone bring up before has bothered me off and on: since the world is round, won't any direction Muslims pray at be facing Mecca?

Update: no, it's not! See the comments for explanations by people who didn't have to struggle not to fall asleep during Geometry 1.

Comments (6)


To explain this, I need to start with the term "great circle" as it applies to spherical geometry. A great circle is the largest possible circle on the surface of a sphere. The equator on a globe is one example, but it's not the only one. You can think of others by moving the equator around without changing its size or equivalently turning the global in various directions.

Great circles serve as "lines" on a sphere, so that for any two points on a sphere, there is exactly one great circle that touches both those points, just like there is exactly one line between any two points on a plane.

Therefore, if you are at one point on a globe, and Mecca is at another point, there is exactly one great circle that touches both, and therefore exactly two directions that face Mecca. All other directions mark different great circles that don't touch Mecca.

All of this is the start of what's called "non-Euclidian geometry", if you've ever pondered late in to the night about it.

Simpler explanation (which of course came to me as soon as I hit "Post") --

If you face due north or south, you are facing only places with the same longitude. Therefore, unless you're at the same longitude as Mecaa, south and north at least are wrong directions.

All of this is the start of what's called "non-Euclidian geometry", if you've ever pondered late in to the night about it.

No, I can't say that I have. As a matter of fact, I know about as much about Eclydi-- Eucalyptus -- whatever it is as Muslim "scientists" know about magnetic fields. "Math is hard," Barbie said.

Jim C. [TypeKey Profile Page]:

A bit simpler. Suppose the Earth had no mountains and the oceans were filled in. Start walking straight in some direction without turning. There are only 2 directions you could head in where you would wind up in Mecca, 180 degrees apart. The shorter is the one they pray to.

The same is true of any two points. Start from your house. Assume all the buildings are flattened. To get to the center of Orlando, there are only 2 directions you can head in. One of them takes a lot longer.

I would love to take a Muslim person (say, 0ne of those obnoxious imams that are always spouting off, or the Scientific Genius™ in the article linked in the post) and spin them around and around, and then tell them "now figure out where Mecca is." Then I would make them do geometry problems.

Steve Skubinna [TypeKey Profile Page]:

Darn, I see others have chimed in with the Great Circle idea. But yes, you can draw a Great Circle that has both your position and Mecca's along it, but it isn't a random direction.

I just got my Third Mate's license and had to dust off celestial and terrestrial navigation concepts I haven't used since Navy OCS almost thirty years ago.

Spherical trig is a big subject to get your mind around, especially if, like me, one is a Bear of Very Little Brain.

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