Fig. 1: Timescales of GPM stimuli.

Left: inward (type II) migration of a proto-Jupiter and proto-Saturn within gaps in the gaseous protoplanetary disk (in brown, white arrows indicate motion). The Solar System’s gaseous disk dissipated ≤5 Myr_ss (ref. ³⁶). Right: a giant planet instability (giant planets on high-eccentricity orbits) in the presence of an outer planetesimal disk. Such an instability might be caused by dissipation of the gaseous disk, a giant planet orbital configuration that is inherently unstable without the presence of the gaseous disk, or interactions with an outer planetesimal disk. Gas dissipation occurs between 3 Myr_ss and 5 Myr_ss (black box), destabilization of a self-unstable system occurs ≤10 Myr after gas dissipation (~5–15 Myr_ss), and planetesimal disk-triggered instability occurs within 100 Myr of gas dissipation¹⁶. An LHB scenario occurs >400 Myr_ss, beyond the scale of the timeline. Note that each scenario corresponds to a distinct timeframe in Solar System history, and the resultant dynamical excitation scatters inner Solar System bodies (black dots). Myr_ss reflects million years after Solar System formation, assigned to the age of the oldest CAIs.