This graph is from the teacher’s answer key for the Voyage grade 5-8 lesson Round and Round We Go – Exploring Orbits in the Solar System. The lesson looks at dynamics in the Solar System, and includes two inquiry-based hands-on activities.

The first activity explores the nature of an ellipse based on its mathematical properties, including the concept that all possible ellipses can be described by the same numerical model. Objectives include: an understanding of the mathematical parameters that define and characterize an ellipse; developing the ability to precisely draw an ellipse; understanding how the shape—the eccentricity—of the ellipse changes with a change in the distance between the foci; and an understanding that objects orbiting the Sun travel in ellipses of varying size, eccentricity, and spatial orientation.

In the second activity the class explores how they might create a good model of the orbits associated with the Solar System. They recognize that if they are given the parameters of each object’s elliptical orbit they can create the model.

This graph is created by the student based on the real orbital parameters of the Solar System that are provided. The student then explores the nature of the generated ellipses and sees that the planets orbit the Sun in nearly circular orbits. But the orbits for a comet and a trans-neptunian object have far more elliptical orbits than the planets. This is also the case for Pluto, which indicates that Pluto may not be a planet but rather one of the largest of the trans-neptunian objects.