How were planets in the solar system formed

Answer 1

The formation of planets in the solar system can be attributed to the following process, known as the nebular hypothesis:

1. Nebula Formation: A nebula, a massive cloud of gas and dust, formed in space due to the gravitational collapse of a molecular cloud composed mostly of hydrogen and helium.

2. Protostar Formation: Within the nebula, regions with higher density and gravitational attraction began to collapse further, forming a protostar at the center of the cloud. The protostar gradually accumulated more mass from the surrounding gas and dust.

3. Accretion of Planetesimals: As the protostar in the center grew, the surrounding material started to flatten into a rotating disk known as the protoplanetary disk. Within this disk, small particles called planetesimals formed due to the collision and sticking of dust and ice grains. Over time, these planetesimals continued to grow through mutual gravitational attraction, forming larger objects called protoplanets.

4. Clearing of Orbit: As the protoplanets grew, they cleared their orbits by gravitationally attracting and assimilating nearby planetesimals or by ejecting them from their orbits. The clearing of orbits allowed the protoplanets to continue accumulating mass.

5. Terrestrial and Gas Giant Planet Formation: In the inner regions of the protoplanetary disk, close to the Sun, only rocky materials could condense due to high temperatures. This led to the formation of the terrestrial planets (e.g., Mercury, Venus, Earth, and Mars). In the outer regions, where temperatures were colder, icy materials could also condense, resulting in the formation of gas giant planets (e.g., Jupiter, Saturn, Uranus, and Neptune). These gas giants captured and retained substantial amounts of hydrogen and helium gases.

6. Final Stages: The protostar at the center of the disk, now referred to as the Sun, reached a stable phase through nuclear fusion, releasing energy in the form of sunlight. At this stage, the remaining gas and dust in the protoplanetary disk was either assimilated by the growing planets or blown away by the solar wind.

It is important to note that while the basic steps of planet formation are understood, there are still ongoing research and debates about the exact details and mechanisms involved in the formation of each individual planet in our solar system.