What is the role of the circumstellar disk in the formation of the solar system?

The circumstellar disk played a critical role in the formation of the solar system. It was a rotating disk of gas and dust that surrounded the young sun and extended outward to the current orbit of Neptune. The material in the disk was heated by the sun and collisions caused it to stick together to form larger and larger clumps.

Eventually, these clumps grew into planetesimals, which were several kilometers in size. These planetesimals collided and merged to form the planets, moons, and other bodies that make up the solar system.

The composition of the planets was influenced by their distance from the sun, as the temperature and pressure in the disk varied with distance. The inner planets, which formed close to the sun, are primarily composed of rock and metal, while the outer planets are primarily composed of gas and ice.