According to the nebular theory, how did the solar system form?

1. The nebular theory states that our solar system formed from the gravitational collapse of a giant interstellar gas cloud—the solar nebula.
2. (Nebula is the Latin word for cloud.)
3. Kant and Laplace proposed the nebular hypothesis over two centuries ago.
4. A large amount of evidence now supports this idea.

The nebular theory is a widely accepted model used to explain the formation of the solar system. According to this theory:

• Nebula Formation: The solar system began to form from a giant, rotating cloud of gas and dust known as a nebula. This nebula was primarily composed of hydrogen, helium, and trace amounts of other elements.
• Gravitational Collapse: Some triggering event, such as the shockwave from a nearby supernova or the compression of the nebula due to gravitational disturbances, caused the nebula to start collapsing under its own gravity.
• Formation of a Protostar: As the nebula contracted, it started to spin faster and flatten into a spinning disk due to conservation of angular momentum. In the center of this disk, a protostar formed—a dense, hot core composed mainly of hydrogen gas.
• Accretion of Planets: Within the spinning disk surrounding the protostar, smaller particles of dust and gas began to collide, stick together, and gradually accumulate into planetesimals—smaller bodies that eventually grew into protoplanets. These protoplanets continued to grow through collisions and gravitational attraction, forming the planets and moons of the solar system.
• Differentiation and Formation of Solar System Bodies: As the protoplanets accreted more material, they underwent differentiation, with heavier elements sinking toward their cores and lighter elements rising to the surface. This process led to the formation of rocky planets closer to the Sun and gas giants farther away. Moons, asteroids, comets, and other celestial bodies also formed through similar processes.

The nebular theory provides a comprehensive explanation for the formation of the solar system, based on the observations of star formation in other regions of space and the similarities in composition and motion among the bodies in our solar system.