The Solar System is believed to have formed from the gravitational collapse of a massive interstellar cloud of gas and dust, often referred to as a solar nebula. As this nebula contracted, angular momentum caused the material to spin and flatten into a protoplanetary disk surrounding a central core. Within this disk, the rapid accumulation of mass led to the formation of the Sun. Over subsequent millions of years, gravitational instability and particle collisions initiated a process of accretion, where planetesimals aggregated into larger bodies. The resulting architecture shows a gradient of composition: inner planets primarily formed from refractory materials due to the limited temperature range, while the outer gas giants accumulated massive amounts of volatile compounds from the remaining nebula gas. This accretionary evolution established the distinct orbits, orbital dynamics, and structural components observed throughout the modern system.