The solar system is made up of gigantic clouds of gas and dust that collapses and then forms the stars and planets in them.
But what about the details?
The story begins with the birth of a star we know by the name of the Sun, 4.6 billion years ago.
Ever since in the Milky Way galaxy,, there are huge clouds of gigantic molecules with a mass of 105 to 106 solar masses with the smallest molecular clouds measuring 0.1 to 10 solar masses. These molecular clouds are dominated by Hydrogen and Helium and are followed by other elements such as Carbon, Nitrogen, and Silicates in very small quantities.
At first molecular clouds are in stable condition but can collapse if there is a disturbance that causes instability.
The process of forming the Solar System.wikimedia
One day, there came a shock wave from the enormous explosion of a nearby star. As a result, gaseous particles and dust form spherical and dense spherical clouds. Clouds also collapse, starting from material accumulation to the core. The more matter that is drawn to the core, the more gravity increases. During collapse/shrinkage occurs, the core rotates faster and the temperature increases.
In the end, the nucleus has enough energy to start the combustion reaction of hydrogen to become helium. So immediately began a nuclear reaction that can release enormous energy. This is called the birth process of stars that we know very well as the Sun which has a mass of 99.8% of the cloud mass.
Well, what about the formation of planets?
Not all matter in the molecular cloud forms the Sun. There is still some dust and gas forming a disk around the Sun so that it will look like a disc with a giant gas ball glowing in the center. The particles present in the disk are filled by 75% hydrogen, 25% helium, and 2% other elements. They move in circular orbits around the Sun.
Although the temperature in the core area increases sharply, further away from the core the temperature is lower. Therefore, the material in the core area will easily evaporate, while the gas in the distant and cold areas will remain in the gas condition.
The material in the disk then condenses to form solid or liquid particles. Granules formed near the Sun are solid granules including aluminum, titanium, iron, nickel, and silicate.
On the edge of the disk, the temperature is low enough that the hydrogen molecules condense to form ice from ice water, frozen methane, and frozen ammonia. The temperature difference between the area near the star and the area away from the star becomes the key difference from the planet that will form.
The particles in the disk interact and combine to form tiny microscopic grains. The period of planet formation is a harsh and cruel period. How come! The grains on the disk move and collide with other grains. The result is that the granules then combine to form larger and denser particles. Collisions between particles continue to occur and the particles then form a small planet or planetesimal.
This merging process continues to occur and planetesimal continues to grow larger which later became known as protoplanet or planetary embryo. Protoplanet in its interactions attracts planetesimal with similar compositions to join and form planets.
As the farther the temperatures get lower, then near the Sun, planetesimals are formed in the form of rocks and metals because the gas is definitely evaporated. And formed rocky planets like Mercury, Venus, Earth, and Mars.
Furthermore, apart from rocks and metals, planetesimal is also formed from iced fragments. The interaction between planetesimals composed by rocks, metals and ice fragments with other planetesimals forms the giant planet's core. The core is very large and able to capture hydrogen and helium gas to form a very thick atmosphere. In the end, formed a giant planet rich in hydrogen and helium with a compacted rock core.
If we explore the farther into the outside of the disk, then the condition becomes colder. Very cool because the temperature is getting lower. In that cold outer area, there is still planetesimal ice that survives and forms small objects measuring several kilometers. These small objects are known as objects in the Kuiper Belt. Some objects in the Kuiper belt have a size large enough like Pluto, Makemake, Sedna, Eris which then classified as a dwarf planet because it is unable to "clean" the area around it from another planetesimal. So if these objects are a planet, then its gravity is enough to attract other objects around it to join or toss it outside the Solar System.
Meanwhile, the area between Mars and Jupiter is also filled by other small objects known as asteroid belts. In this area, the planetesimal collection of stones measuring a few meters up to 1000 km moves around the Sun. Planetesimal in this area is the rest of the formation of the Solar System that did not manage to form a planet due to gravitational disturbance from Jupiter.
Natural Satellite & Giant Planet Rings
The planets in the Solar System are known to have a companion or a natural satellite that surrounds. For the giant planet, the natural satellites are believed to be formed through a process that is almost identical to the birth of the planet. In the early days of the formation of giant planets, there is a large amount of gas that surrounds the planet which then interacts to form the satellites that surround the planet.
For Mars, the satellite companion is formed elsewhere and then captured by Mars to get around it. While the companion of Earth, the Moon, formed through the impact of the Earth's collision with an object suspected of Mars and then the rest of the collision that became the forerunner of the Moon that surrounds Earth. While the nearest planet to the Sun of Mercury and Venus does not have satellites, because if there are satellites there then the satellite will not survive.
In the process of forming the entire planet in the Solar System, when a giant planet is formed, the planetesimal that moves closer to the planet will be torn apart by gravity and its fragments are then trapped orbiting the giant planet as a ring.
So far so we understand the history of the Solar System in which we live. The discovery of other details in the Solar System as well as in other planetary systems will further enrich our understanding. Thanks!
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references and related reading :
https://www.space.com/25126-big-bang-theory.html
https://www.big-bang-theory.com/
https://www.space.com/35526-solar-system-formation.html
http://www.phy.olemiss.edu/~luca/astr/Topics-Solar/Formation-N.html
https://www.space.com/16080-solar-system-planets.html
http://www.theplanetstoday.com/the_planets.html
https://phys.org/news/2015-01-planets.html
https://www.sciencelearn.org.nz/resources/271-natural-satellites
https://www.britannica.com/science/moon-natural-satellite