::Thanks so far. On my second point (which is more of a personal suggestion), I think that omitting the "the"s as the current caption does is a bit awkward. Consider the current wording: 
 :::Motion of barycenter of Solar System relative to the Sun 
 ::versus my suggestion: 
 :::Motion of the barycenter of the Solar System relative to the Sun 
 ::If you think the former is better, feel free to leave it as is. (Just wanted to note the difference since you appear to have overlooked my suggested addition of two "the"s.)