Secular resonances
Secular resonances appear when the slow precession of a small body's orbit comes into sync with one of the eigenfrequencies of the planetary system. Unlike mean-motion resonances, these operate on timescales of millions of years — but their effects are profound: they define the boundaries of the asteroid belt, reshape collisional families, pump up eccentricities and inclinations, and open transport routes that send fragments toward planet-crossing orbits. This collection covers the mapping of linear secular resonances in the Solar System from 2 to 50 AU, a detailed survey of nonlinear resonances (up to high order) throughout the main belt and their interaction with asteroid families, and recent efforts to automate the identification of resonant asteroids using classical machine learning, advanced methods such as Vision transformers, and LLMs — a growing necessity as catalogs approach millions of objects.