The nebular theory, also known as the nebular hypothesis, is the most widely accepted model for explaining the formation and evolution of the Solar System. It proposes that the Solar System formed from a spinning cloud of dust and gas, called a nebula, which flattened into a protoplanetary disk and eventually became a solar system consisting of a star with orbiting planets/08%3A_Earth_History/8.02%3A_Origin_of_the_Solar_SystemThe_Nebular_Hypothesis). The theory explains several key characteristics of the Solar System, including the nearly circular and coplanar orbits of the planets, their motion in the same direction as the Suns rotation, and the differentiation between the rocky planets within the asteroid belt and the gaseous planets outside of it. The orderly motions of the solar system today are a direct result of its beginnings in a spinning, flattened cloud of gas and dust. The nebular theory also accounts for the existence of the Kuiper Belt, a region on the fringes of the solar system with a high concentration of comets.
The nebular theory suggests that as the solar nebula collapsed, temperatures continued to increase, the solar nebula spun faster and faster, and the solar nebula disk flattened, leading to the formation of planets within this disk. The theory also explains the distinct temperature zones that developed within the nebular cloud, leading to the differentiation in the composition and size of the planets/08%3A_Earth_History/8.02%3A_Origin_of_the_Solar_SystemThe_Nebular_Hypothesis). Overall, the nebular theory provides a comprehensive explanation for the formation and characteristics of the Solar System, and it is supported by a wide range of evidence and observations.
