Eradiate is a new open-source 3D radiative transfer model designed to provide highly accurate results for various applications in Earth observation and atmospheric science. Its Monte Carlo ray tracing radiometric kernel is derived from Mitsuba 3, a research-oriented rendering system, and therefore benefits from many technological advances made in the computer graphics community. This foundation unlocks a path to improving radiative transfer simulation accuracy by facilitating the integration of models and numerical techniques developed by scientific communities that are otherwise compartmentalized. Eradiate currently covers the [250 nm, 3 μm] spectral region and offers advanced 3D surface modelling features, as well as a state-of-the-art 1D atmospheric model (plane-parallel and spherical-shell) and polarization support. Designed for modern scientific Python programming workflows, it is intended for use in interactive Python sessions such as Jupyter notebooks. Eradiate is thoroughly tested and validated against various radiative transfer benchmarks, ensuring its suitability for calibration and validation tasks. This paper introduces Eradiate from historical, scientific, and architectural perspectives. It elaborates on its feature set and showcases a variety of applications, with scenes ranging from simple 1D plane-parallel setups to complex, fully resolved 3D vegetated canopies and even large regions on Earth.