Study the Orbital Motions of Comets
The most famous comet is probably Halley's comet, which has a rather eccentric elliptical orbit.
Comets have a variety of orbits, with eccentricities that vary from nearly circular to hyperbolic. You can use distinct colors for the various orbit types.
In December of 2018, comet 46P/Wirtanen made a close pass of Earth. You can visualize the positions of the Earth and the comet as follows.
You can view the scene from a couple of different vantage points to observe the different orbital inclinations involved.