Mar 2018

Meet Me in the Middle

Two points, A and B, are located on the surface of a smooth sphere having a radius of 6.371x106 meters. Positions of the two points a







24°54’04” S

59°09’52” W


33°35’24” N

07°36’14” W

What are the midpoint latitude and longitude of the shortest distance on the sphere between the two points?





   S       D       B       Total    Name      Date      Comments
4 10 3 17 Dave Tlusty 20 Mar  Dave found an online midpoint calculator but must have punched in something incorrectly because his latitude was 30” off.
2 10 4  16 Chris Ruetten 20 Mar Chris' solution came in at the same time as Dave's. He used end point averages which threw his lat and long off ~19’ and ~10’, respectively.
6 8 3  17 Larry Schmit 27 Mar  Larry used vector operations on his HP48GX calculator to come up with the correct answer.
6 6 5 17 Norm Hanson 17 Jun Norn's solutin can in after the June newsletter went to press so he wasn't identified as a problem solver. Norm's answer was correct ahd his detailed solution is included here.

updated 28 Mar 2018