The energy budget and figure of Earth during recovery from the Moon-forming giant impact

TL;DR

This paper calculates the early Earth's energy budget after the Moon-forming impact, revealing significant changes in Earth's structure and energy components that influence tidal evolution and thermal history.

Contribution

It provides a comprehensive calculation of Earth's energy budget during its post-impact evolution, including all relevant energy components, using impact simulations and planetary models.

Findings

Earth's figure and internal structure changed substantially post-impact

Kinetic, potential, and internal energy changes were significant

Implications for early Earth's tidal dynamics and thermal evolution

Abstract

Quantifying the energy budget of Earth in the first few million years following the Moon-forming giant impact is vital to understanding Earth's initial thermal state and the dynamics of lunar tidal evolution. After the impact, the body was substantially vaporized and rotating rapidly, very different from the planet we know today. The subsequent evolution of Earth's energy budget, as the body cooled and angular momentum was transferred during lunar tidal recession, has not been accurately calculated with all relevant energy components included. Here, we use giant impact simulations and planetary structure models to calculate the energy budget at stages in Earth's evolution. We show that the figure and internal structure of Earth changed substantially during its post-impact evolution and that changes in kinetic, potential, and internal energy were all significant. These changes have important implications for the dynamics of tidal recession and the thermal structure of early Earth.