Giant planets

…discussion compares scenarios in which giant planets formed near their present orbits with models involving substantial migration from a more compact configuration. It considers why the Lucy spacecraft’s observations can test these ideas and how discoveries of other planetary systems sharpen the questions.

…Instability among the giant planets sent some bodies toward the terrestrial planets. Noble gases preserved in Earth's atmosphere provide evidence for the scale of this bombardment and help relate its timing to the growth of Earth.

…on the dynamical history of the giant planets.

When did the giant planets become dynamically unstable? This lecture compares evidence from lunar impact craters, binary objects in the Kuiper belt and dynamical models. It explains why these constraints matter for reconstructing Solar System evolution and why the timing remains an unresolved research question.

The Kuiper belt preserves evidence of major orbital changes among the giant planets. This lecture reviews migration-driven explanations for its resonant, dynamically excited and detached populations. It then examines why these early models required an additional instability mechanism, leading to scenarios involving resonance crossing between Jupiter and Saturn.

This lecture connects the properties of the giant planets to their diverse populations of moons and co-orbiting small bodies. It focuses on irregular satellites, whose inclined and elongated orbits suggest capture, and on Trojan objects that move around stable configurations associated with Jupiter or Neptune.