needs work   A very wordy article for a simple concept Mean longitude is just the angular distance from a reference direction which a body would have if it moved at a uniform angular rate rather than the nonuniform rate which occurs because of an elliptical orbit Thats it The second paragraph is discussing in a convoluted repetitive fashion socalled mean elements which have nothing to do with mean longitude Mean elements are a sort of average over a long time period Yes you can have a mean longitude as part of a set of mean elements but this mean mean longitude thing is a little contrived I had to search for it to find out what it was supposed to be and only came up with a couple of hits