  We investigate the possibility that the Moon's formation impact was triggered
by an early dynamical instability of the giant planets. We consider the
well-studied "jumping Jupiter" hypothesis for the solar system's instability,
where Jupiter and Saturn's semi-major axes evolve in step-wise manner from
their primordially compact architecture to their present locations. Moreover,
we test multiple different configurations for the primordial system of
terrestrial planets and the Moon-forming projectile, with particular focus on
the almost equal masses impact. We find that the instability/migration of the
giant planets excites the orbits of the terrestrial planets through dynamical
perturbations, thus allowing collisions between them. About 10% of the
simulations lead to a collision with the proto-Earth which resulted in a final
configuration of the terrestrial system that reproduces, to some extent, its
present architecture. Most of these collisions occur in the hit-and-run domain,
but about 15% occur in the partial accretion regime, with the right conditions
for a Moon-forming impact. In most of the simulations, there is a delay of more
than ~20 My between the time of the instability and the Moon-forming impact.
This supports the occurrence of an early instability (< 10 My} after
dissipation of the gas in the proto-planetary disk), compatible with the time
of the Moon-forming impact (30-60 My) inferred from cosmochemical constraints.
In general, the final states of the inner solar system in our simulations show
an excess of Angular Momentum Deficit, mostly attributed to the over-excitation
of Mercury's eccentricity and inclination.
