[BITList] Great Circle & Rhumb Lines

[Michael Feltham]

On Monday night I was watching a documentary on BBC4 called "Science &  
Islam".  It was  by an Anglo/Iraqi Professor from an English  
University and was very interesting, last night's programme was about  
the work of an Arab astronomer and mathematician, Al-Biruni.  It  
appears he was able to calculate the circumference of the Earth many  
centuries ago.

One of the topics raised was how Muslims always have to pray in the  
direction of Mecca.  In Washington,D.C. they have built a new Mosque,  
during construction the question arose as to the direction of Mecca.   
Everyone assumed that the direction would be a straight line, (a Rhumb  
Line ) from the States to Mecca but the Professor said that it was not  
correct, it would be a Great Circle.

I am sure this is wrong as when sailing a Great Circle across e.g. the  
Atlantic or Pacific you alter course frequently to keep the ship's  
track on the Great Circle Course.  Perhaps someone who hasn't retired  
such a long time ago could clear the matter up !

Mike