Even in one dimension, the average and median don't have to be the same. In a list of numbers 1,2,3,4,100, the median is 3 but the average is 22. Same thing is

Even in one dimension, the average and median don't have to be the same. In a list of numbers 1,2,3,4,100, the median is 3 but the average is 22. Same thing is done here, with same formulas to obtain them, just a two dimensional version (and some modifications to account for the meridians meeting at the poles, see the document linked by GP).