You have until 2027 to figure it out. That's when Pluto crosses inside Nepune's orbit again.
Go to Odintown, ask for Bill, he will help.
I still can't figure how anything can travel in an elliptical orbit. It's like saying gravity is weaker at the outer aspects of the orbit. Since other stars are considerably far off, that seems hard to understand how there gravity filed could make such a difference in the orbit of one of our outer planets. Now I'm curious, and I'll have to do some research.
Ah, size matters, especially to matter. Apparently Neptune has a profound affect on Pluto's "chaotic" orbit. There is a 3:2 resonance with the orbit of Neptune, and a 17 degree incline in the orbital ellipse of Pluto. The two realign to a original origin every 500 years. The two can never collide, because Pluto orbits above Neptune at the point the orbits cross.
There would be two math challenges here. One to get the path of a chaotic elliptical orbit based on changing gravitational forces, and the other, a lot easier, to warp that 17% tilt into a 2-D plane.
Oh, I almost forgot my favorite planet, Jupiter. Earth lost out when Obama became President, but I digress... Anyway, Jupiter is so big it actually doesn't orbit the sun. The orbital path would need to be adjusted for the combined gravity Jupiter and the Sun exert on each other. That influence is negligible for other smaller planets but, "... the gas giant is so big that its center of mass with the sun, or barycenter, actually lies 1.07 solar radii from the middle of the sun— or 7% of a sun-radius above the sun's surface. Both the Sun and Jupiter orbit around that point in space.
Pete