Using Moment of Inertia and Observable Planetary Features to Approximate the Two-Layer Structure of Earth, Jupiter, and Neptune

Abstract

This paper examines the interior structure and composition of Earth, Jupiter, and Neptune by using moment of inertia (MoI) and observable planetary features to create approximate two-layer interior structure models. The moment inertia of a uniform sphere, hollow sphere, and a sphere with a shell are derived to calculate the radius and density variables that identify the relationship between the different radii and densities of the two layers. A two-layer model of the planet’s interior can then be formulated based on the radius, density, known MoI factor and the surface density or the assumed composition density of the planet. The models created for Jupiter and Neptune are compared to Earth’s model and conclude that Jupiter may have a silica-rich core, whereas Neptune’s model has inconclusive density and radius results that should be further investigated. Published literature containing current three-layer models of planetary interiors confirm the results produced from the two-layer models in this paper.