The authors propose that the Late Heavy Bombardment (LHB), a period of intense cratering on the Moon, was triggered by the rapid migration of the giant planets after a long quiescent period. During this migration, the planetesimal disk outside the orbits of the planets destabilized, leading to a sudden delivery of planetesimals to the inner Solar System. The asteroid belt was also strongly perturbed, supplying a significant fraction of the LHB impactors. The model explains the LHB and reproduces observational constraints of the outer Solar System. The key mechanism involves the 1:2 mean motion resonance (MMR) crossing between Jupiter and Saturn, which caused an instability in their orbits and scattered objects into the inner Solar System. The model predicts a sharp increase in the impact rate at the beginning of the LHB, with a total mass of 9 × 10^21 g striking the Moon, and a similar amount of cometary material. The asteroid belt was depleted by a factor of about 10 during the LHB, and the duration of the LHB is estimated to be between 10 and 150 million years. This model provides a coherent explanation for the LHB and aligns with current observations of planetary orbits and asteroid belt dynamics.The authors propose that the Late Heavy Bombardment (LHB), a period of intense cratering on the Moon, was triggered by the rapid migration of the giant planets after a long quiescent period. During this migration, the planetesimal disk outside the orbits of the planets destabilized, leading to a sudden delivery of planetesimals to the inner Solar System. The asteroid belt was also strongly perturbed, supplying a significant fraction of the LHB impactors. The model explains the LHB and reproduces observational constraints of the outer Solar System. The key mechanism involves the 1:2 mean motion resonance (MMR) crossing between Jupiter and Saturn, which caused an instability in their orbits and scattered objects into the inner Solar System. The model predicts a sharp increase in the impact rate at the beginning of the LHB, with a total mass of 9 × 10^21 g striking the Moon, and a similar amount of cometary material. The asteroid belt was depleted by a factor of about 10 during the LHB, and the duration of the LHB is estimated to be between 10 and 150 million years. This model provides a coherent explanation for the LHB and aligns with current observations of planetary orbits and asteroid belt dynamics.