This chapter studies the emergence of a new technological initiative jointly conducted by the European Space Agency and the European Union: the vision of a digital twin Earth (DTE). The idea behind the DTE is to combine various technologies, including satellite Earth observation, advanced computer models, and AI, to build a digital replica of our planet and thereby predict and visualize (future) risks emanating from global environmental changes. The chapter traces the competing actor coalitions advancing DTE projects and discusses the underlying imaginaries and discourses. Understanding the DTE as a sociotechnical imaginary allows us to understand why this vision, which has been around for decades, has gained traction within the EU. This perspective highlights how the development of European space and supercomputing infrastructures (as the required technologies behind the DTE) was co-produced with discourses of European digital sovereignty and a redirection of security toward complex planetary threats. To establish these arguments, the contribution draws on participant observation at major European space policy events (2018–2021), discourse analysis of key policy documents on the DTE and the broader European Earth observation program Copernicus, and 22 semi-structured interviews with experts from different parts of the space policy field.