Planetary processes such as impacts, volcanism, tectonics, climate change and greenhouse-gas warming shape our solar system in surprising ways.
Impact processes clearly played a crucial role in bringing the solar system to its present state. A solar system-wide rain of projectiles had a profound effect on all of the planets, delivering volatiles and organic material from the colder outer solar system to the inner planets while at the same time causing frequent, catastrophic impacts. The geologic record of this period has long since vanished from Earth, but important links to this era still exist on the Moon and in the outer reaches of the solar system, home of short-term comets and the Kuiper Belt. Additional evidence may exist in the highlands of Mars and a few spots on Venus.
The terrestrial planets formed at about the same time, in the same general region of space and experienced similar forces and processes during their development. Yet today they are different for a complex set of reasons that we are only beginning to understand. It is possible, for example, that Venus once harbored warm oceans that were lost into space. The causes of such climate change are complex and their interactions not fully understood, but they are clearly of tremendous importance to our home planet.
Models also suggest that giant planet formation is a critical feature of planetary systems in general, and may govern the formation and early evolution of rocky inner planets that can possess habitable environments. Detailed study of the gas giants Jupiter and Saturn, ring systems, and the Kuiper Belt will significantly enhance our understanding of the general processes of solar system formation and evolution.
NASA Solar System Exploration Planetary Database