ASTR 450
Dynamical Evolution of the Solar System

The Solar System was formed in a state which differs from that observed today by 4.5 billion years of dynamical evolution. By studying the details of this evolution, we learn more about the conditions prevalent shortly after the Solar System's formation. We can also understand our Solar System better by studying the evolution of others like it. The figure shows that solar perturbations acting on planetary satellites on polar orbits rapidly destabilize the orbits. If our Moon's orbit were inclined by 90 degrees out of the ecliptic, it would crash into the Earth in ~6.5 years! This is part of the reason that no satellites in the Solar System have highly-inclined orbits! Similar dynamics causes some comets to become Sun-grazing and also allows Oort cloud objects to enter the inner Solar System.

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