I'm trying to determine the length of time Pluto spends above/below the ecliptic. I've got these figures: semi-major axis: 39.264 AU semi-minor axis: 34.031 AU orbital eccentricity: 0.249 approx orbital circumference: 230.85 AU orbital inclination is 17.142° (I'm thinking this number isn't relevant to this question) So I guess what I'm asking is, given those figures, how do I determine the "section" of the circumference that is above/below the ecliptic? Or is there additional info I need such as the location of the sun as a focus within the ellipse? The ultimate goal here is to learn how planetary transits can be calculated. Specifically, I was wondering about a schedule of transits across the sun of planets as viewed from Pluto. Thanks for any assistance.