Latitude Half Circumference of Equator ```Name: Linda K. Status: Teacher Age: 50s Location: N/A Country: N/A Date: July 2001 ``` Question: What parallel has half the circumference of the Equator? Replies: Linda, This question is similar to one that I answered before, but with a specific latitude twist. The circumference at the equator is pi (3.1416) times twice the radius (r) of the Earth. To find the latitude that you want, take half the circumference at the equator (2 X pi X r/2). We now have to find the cosine of the latitude angle that equals 0.5 (r/2 = 0.5 X r). Either by trial and error or by using arccos, we find that the latitude where the circumference is half that at the equator is 60 degrees. David R. Cook Atmospheric Research Section Environmental Research Division Argonne National Laboratory If the earth were a perfect sphere, it would be 60°. Since the earth is slightly flattened at the poles and bulging at the equator, 60° has a circumference slightly less than this. So, the actual latitude will be slightly lower than 60°, but I do not know the exact number for sure. Since the "oblateness" of the globe is quite small, however, the answer to your question is very close to 60°. Richard E. Barrans Jr., Ph.D. Assistant Director PG Research Foundation, Darien, Illinois Click here to return to the Environmental and Earth Science Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012