The Volatile-Rich Theia Hypothesis

The origin of Earth's water and the Moon remains a central question in planetary science. We propose that Theia, the Mars-sized protoplanet implicated in the Giant Impact Hypothesis, formed earlier than Earth in the same region of the solar system, allowing it to accumulate a greater inventory of volatiles, including water. During the Giant Impact, Theia's volatiles were transferred to Earth, contributing to its water inventory and the formation of the Moon. This hypothesis explains the isotopic similarity between Earth and the Moon, the presence of water in lunar rocks, and the deep water reservoirs in Earth's mantle. Our model provides a coherent narrative for the early solar system's dynamics and the delivery of volatiles to rocky planets.