The Moon is thought to have formed in the final stages of Earth’s formation, from the debris associated with a major collision between the proto-Earth and another Mars-sized planet sometimes called Theia. Although this “Giant Impact” model is widely accepted, increasingly there are aspects of the Moon’s composition that appear inconsistent. New evidence also casts doubt to the theory that Earth’s water and other volatile elements were added after the Moon’s fiery start. Join us to hear Prof Alex Halliday from the Dept of Earth Sciences, University of Oxford discuss the potential origins of the Moon and why we don’t have a self-consistent model to explain its origins.