Unfolding Solar System Formation: An In-Depth Analysis

This detailed exploration delves into the process of how our solar system formed. It traces the journey of our system starting from the birth of our Sun, its stable phase, the formation of planets and even beyond to the migration of outer celestial bodies. So lets embark on this adventure!

The "Nebular Hypothesis" serves as a model for explaining how our solar system came to be. First proposed by figures such as Pierre Simon Laplace, Emanuel Swedenborg and Immanuel Kant in the 18th century this theory has undergone various modifications and enhancements while still maintaining its core concepts.

According to the Nebular Hypothesis around 4.6 billion years ago our solar system originated from a molecular cloud spanning over 65 light years in size. This cloud was primarily composed of hydrogen and helium elements. Over years these massive molecular clouds eventually collapsed and fragmented. The specific cloud that gave birth to our system had fragments measuring approximately 3 3.5 light years in diameter.

The process of gas cloud fragmentation might raise some questions. One plausible explanation could be shockwaves originating from a supernova event that caused local instabilities within the cloud—similar, to waves in an ocean. These instabilities led to denser regions forming within the cloud. Ultimately resulted in fragmentation.

One of these collapses was responsible for the formation of our solar system. The size of proto nebulae can range from a small fraction to several times the mass of the Sun.

If we have a nebula with the mass as our Sun it would go through a collapse lasting around 100,000 years. During this collapse it would become more condensed due to the conservation of angular momentum leading to an increase in its rotation speed. As atoms within the nebula collided at a higher rate their kinetic energy would transform into heat.

The region at the core of the nebula had the concentration of atoms and molecules and experienced the most collisions. This resulted in an area with a temperature higher than that of its surrounding disk.

Over a span of 100,000 years gravity, magnetic fields, gas pressure and rotation caused the protostellar nebula to flatten into a disk that extended up to 200 astronomical units (AU). Within this disks center emerged an young protostar; however hydrogen fusion had not yet commenced.

The spinning protoplanetary disk continuously provided material to sustain and contract the protostar further. This process led to an increase, in its mass, temperature and pressure. 50 million years later reached a critical point where temperature and pressure became high enough for nuclear fusion to initiate—marking the birth of our Sun.

The Suns internal pressure increased as a result of the heat generated by the nuclear fusion process. This increase in pressure counteracted the contraction eventually reaching a state of equilibrium and stabilizing the Sun.

Terrestrial planets primarily formed in the region of the protoplanetary disc. Small dust grains orbiting around the Sun in this area merged together through contact gradually forming objects that were several hundred meters in diameter.

As these celestial bodies gathered material they grew into objects measuring approximately 10 15 km in size at which point gravity played a significant role. These planetesimals exerted forces on each other resulting in collisions. While these impacts caused some disruption they ultimately contributed to growth and accumulation.

The process of accretion outweighed the effects of collisions overall allowing planetesimals to continue growing until only a few remained. These remaining bodies eventually developed into embryos with masses roughly 0.05 times that of Earth. Subsequent collisions and mergers led to the formation of planets as we know them today.

Beyond what's known as the "snow line " planet formation occurred through different mechanisms. In this region various types of ice were present with water ice being particularly abundant both during the disc era and, within our current solar system.

In general the gas giants had an abundance of ices compared to the metals and silicates that make up the terrestrial planets. This allowed the giant planets to gather mass to attract hydrogen and helium. Within a span of 3 million years these planets accumulated around four to five times the mass of Earth.

Afterward a process started where these young gas giants rapidly collected material causing them to grow in size. Prior to planetary migration our early solar system had eight planets with Uranus and Neptune swapping positions, with each other as we see them now. The outer planets were closer together and more compact than they are today. Eventually over time the planets moved into their positions.