Table of Contents
The objective of al Hajj is the Ka’ba
The Need for Directional Information
So what direction is it from here?
Measure using a string on a globe
World map centered on MeccaDirections From Mecca are correct
Directions FROM Mecca are correct
Given the circular appearance of the azimuthal map projection with direction FROM Mecca, we expect a somewhat similar looking circular map with Mecca at the center when requiring directions be TO Mecca.
James Craig of the Survey of Egypt introduced the class of retro-azimuthal map projections in 1910.
Craig’s Retro-Azimuthal Map(squint at it)
Expanded to the whole world this is Craig’s retro-azimuthal map.
Here it is without the graticule.
Changing the latitude of the center changes the map.
Here the center is near the Equator
This is not the end of the story
Equidistant Retro-Azimuthal Centered at Mecca. It covers only the principal Muslin countries (60 degrees in longitudinal extent from the center).
Map of the world centered on Mecca
Changing the center modifies the hole and the overlap.
A new retro-azimuthal projection.Direction to Mecca: Left to Right. Distance: Down.Mecca Is the line across the top. Find your location then measure from the left edge to get the direction. Measure up for distance.
The Graticuleshowing the hole and the overlap.
Distance-direction diagram from Los Angeles Los Angeles across top, Distance down, Direction left to right
The graticule to accompany the previous map
Lines of Equal Direction to MeccaMercator Projection
Or Use The Stereographic projectionCenter near MeccaGreat circles from & to Mecca are straight lines. Local angles are preserved.
On The Stereographic ProjectionTo get the direction to Mecca.Draw a straight line to the center and measure the angle with respect to the meridian.
Here Is A New Azimuthal Projection
Astrolabe by al-Khujandi of Baghdad, A.D. 985
Arab scholars had an interest in astronomical subjects.
An extract of a Qibla table from circa A.D. 1360
Previously only tables and treatises were extant, no maps.
The Iranian Qibla Instrument Found in 1989
Detail of the Qibla Instrument
The second instrument, found in 1995
The second instrument with sundial removed
Waldo Tobler Professor EmeritusGeography Department
|Author: WALDO TOBLER|