Ask A Scientist General Science Archive

Author:     Debbie Miera
Text:       We want to know why a compass that works in the northern 
hemisphere will not work in the southern hemisphere?  We have used a compass 
in Australia and the needle waves back and forth.....without registering a 
particular direction.

Response #:  1 of 2
Author:      Eric Peterson
Text:        A compass will work in the southern hemisphere as well as it does 
in the northern hemisphere.  There are a lot of reasons why your compass may 
not have worked at your particular location -- things such as heavy iron ore 
deposits to spurious magnetic fields being generated by something in your 
area.  The earth has its own magnetic north and south poles.  Without the 
magnetic south pole, the north cannot exist.  It does, of course, vary in 
magnetic intensity at various points on the surface of the earth, so, 
depending upon the quality of the compass, and the surrounding area, your 
particular compass may not work so well.



Response #:  2 of 2
Author:      Robert Topper
Text:        I second Eric Peterson's motion. If compasses did not work when 
you crossed hemispheres it would have been impossible for the early European 
sailors topsail around the world; specifically, they used the same compass to 
come from Spain and Portugal to go around Cape Horn (the tip of South America) 
and onward.  You may have accidentally demagnetized your compass needle, or 
been close to an iron ore deposit....all the things Eric Peterson mentioned.