Getting to know about the formation of planetary systems will be quite interesting. Aren’t you curious to know how this happened?
I am sure you will have numerous questions including when was our solar system formed. What led to this solar system formation and much more?
So, let us dive right into those details without further delay.
1. What Caused the Formation and Evolution of Our Planetary System?
The magnificent formation of our solar system happened a billion years ago. Want to know how many billion? It was a whopping 4.5 billion years ago.
But what made this formation happen? A thick cloud comprising interstellar gas and dust was responsible for the formation of our solar system to happen.
1.1. What Happened Further?
The thick cloud disintegrated likely as a result of the shockwave caused by a nearby exploding star referred to as a supernova. This disintegration resulted in the formation of a solar nebula which is nothing but a spinning, swirling disk of material.
1.2. The Arrival of Our Sun
Gravity pulled the material in at the center. As a result, the pressure in the core increased to a great extent which led the hydrogen atoms to merge to form helium and emit massive energy. This led to the arrival of our very own sun, or you can even say this is how our sun formed. The sun comprises 99.8% of all the mass of our solar system.
1.3. How Did Our Planets Form?
Not only at the center of the disk, but matter away from the center also began to form a cluster, and they banged against each other. As a result, larger objects formed. Of these, a few became big enough for their gravity to turn them into planets, spheres, and even large moons.
This was how the planets were formed. The others which didn’t turn into planets became asteroids, meteoroids, comets, and tiny moons that were irregular.
2. Structure of Our Solar System
We all know about the way our planets are organized in the solar system. But do you know why they are arranged in such a manner? This is because of how our solar system formed. Also, the sun emits quite a lot of heat, and the only material that could endure the heat was rocky material.
Hence for this purpose, Mercury, Venus, Earth, and Mars which are our initial four planets with rocky surfaces are known as terrestrial planets or rocky planets.
2.1. What About the Other Planets?
Materials namely liquid, gas, and ice found their place in the outer region of our solar system. These were brought together by gravity and here we can find our remaining planets – Jupiter and Saturn – the gas giants along with our ice giants Uranus and Neptune.
3. How Did Our Planetary System Come to be Termed the Solar System?
Our planetary system is also referred to as the solar system due to the word solar. Solar is used for depicting things relevant to our sun. Also, do you know where our planetary system is located? You can find it on the milky way galaxy’s exterior spiral arm.
4. More About Our Solar System
Our solar system is not just limited to the eight planets orbiting our sun. There is also the Kuiper belt in our solar system that is present beyond Neptune’s orbit. The bodies which occupy the Kuiper belt are icy bodies that are very tiny. Even the dwarf planet Pluto which is the famous Kuiper belt object is bigger than the icy bodies.
4.1. Oort Cloud
What is an Oort cloud? This giant cloud is the farthermost region of our solar system. It is a giant spherical shell that envelopes our remaining solar system. The Oort cloud appears as a huge, thick-walled bubble comprising icy material of space debris. This debris is similar to the size of a mountain, and at times exceeds it too. You may find the Oort cloud consisting of trillions of objects.
4.2. Astronomical Unit
The distance between the Sun to Earth is illustrated as one astronomical unit. The boundary of our sun’s gravitational pull is the Oort cloud and this is where orbiting objects can retrace their path and come nearer to our sun.
5. What Does the Inner Solar System Contain?
Here is where you can find the terrestrial planets and also the asteroid belt. The objects present in the inner solar system are very near to the sun and they are primarily composed of silicate as well as metals.
6. What Does the Outer Solar System Contain?
Here, you can find our giant planets along with their large moons. You can find these solid objects contain a high volume of volatile substances including water, ammonia as well as methane due to their distance from the sun.
Whereas these are present a little less in the inner solar system due to lower temperatures which permit the compounds to stay solid. Now that we have seen the inner and outer solar system, let us move on to the inner and outer planets.
7. Inner Planets
The planets which belong to this category include Mercury, Venus, Earth, and Mars. What about the composition of these planets? They are majorly composed of refractory minerals namely silicates from which the crust and mantles are formed. Speaking of the core, you can find that it is formed by metals namely iron and nickel.
8. Outer Planets
Which planets can be discovered here? Jupiter, Saturn Uranus, and Neptune belong here and also go by the name giant planets or Jovian planets.
Jupiter and Saturn are massive and hydrogen as well as helium gases are abundant here, and hence they got their name – gas giants. Uranus and Neptune are not as enormous, and ice is the major component here. This is how they obtained the name the ice giants.
9. Asteroid Belt
Ceres is the largest asteroid, and excluding this, other asteroids are categorized as small solar system bodies. Their primary composition consists of rocky and metallic minerals as well as some ice.
The asteroid belt is considered to be fragments from the solar system’s formation that couldn’t combine due to the gravitational interference of the planet Jupiter. The population of the asteroid belt is very sparse.
Our solar system comprises many moons that exceed 200 in number, and it doesn’t stop with this. There are more moons in the pipeline which are yet to be identified.
However, of the eight planets, there are a few planets that don’t have any moons. Want to know which are those planets? They are Mercury and Venus. Where do our giant planets Jupiter and Saturn stand? They are the leaders containing the maximum number of moons.
10.1. Does the Dwarf Planet Pluto Contain Moons?
The answer is yes. It has five moons, not simply one or two. Of these, the moon Charon is very large making the dwarf planet Pluto sway.
10.2. What About Our Very Own Planet Earth?
Our planet consists of the sole natural satellite – the moon. You can find it bright and shining in the night sky and an absolute treat for our eyes. Speaking of natural satellites, there are two small ones present on the planet Mars. These natural satellites may either be the captured asteroids or the debris emitted from a huge impact in the early history of Mars.
11. Milky Way Galaxy
It is in this exterior spiral arm of the milky way galaxy where we can find our planetary system. Also, thousands of planetary systems have been identified that orbit other stars present in a milky way.
Also, have you wondered what is present beyond our solar system? Well, planets are the ones present and they surpass the stars in the night sky.
The earth is the planet that we call our home. Of all the larger planets, our earth is the fifth largest one. Our planet boasts of comprising liquid water on the surface.
Are you not interested in knowing how our planet earth formed? Our planet formed when gravity pulled the gas and dust particles in and resulting in the earth becoming the third planet from the sun.
12.1. Earth’s Orbit and Rotation
The earth takes 23.9 hours to complete a single rotation as it orbits the sun. The number of days taken is 365.25 for the completion of one trip around the sun. However, as per our calendar, one year equals 365 days. Then how is this extra quarter of a day accounted for?
To tally this, once in four years, a day is added. Guess what day and year is called? They are nothing but the leap day and our leap year. The added day is the leap day, and the year in which it gets added is the leap year.
12.2. Formation of Seasons
There is a tilt that causes the occurrence of our seasons. When the northern hemisphere tilts towards our sun, and the southern hemisphere tilts away from the sun, the heat of the sun is higher in the north which results in the summer season there.
In the south, the heat of the sun will be less resulting in the winter season here. So, what about the spring as well as the fall seasons? At the start of these seasons, the sun produces an approximately equal amount of heat in both hemispheres.
It is now time to view the models described by scientists explaining the way the planets formed.
13. Models Described by Scientists
13.1. Core Accretion
The core accretion is the primary as well as the most widely accepted model. However, this model has its share of drawbacks too. This model can be referred to know the way the rocky terrestrial planets formed, yet the same cannot be said when it comes to the formation of giant planets.
13.2. More About the Core Accretion Model
This model explains how the terrestrial planets started as dust grains as well as the way the asteroids, comets, and moon came into existence. As we saw earlier, our solar system was initially a cloud of gas and dust which is nothing but the solar nebula. Then arrived our sun.
The core accretion model states that once the sun arrived, the remaining material started to become a cluster. Small particles were drawn close to each other due to the power of gravity into larger particles to form larger bodies.
The lighter elements including hydrogen as well as helium were carried away from the closer regions by the solar wind. Hence the remaining was only rocky material which was heavy, and this formed the terrestrial world.
13.2.1. Formation of Asteroids, and Comets
Meanwhile, the solar wind did have a great impact on the lighter elements which led them to fuse into gas giants. This is how asteroids, comets, moons, as well as planets came into existence.
According to exoplanet observations, core accretion is a dominant formation process. There are more giant planets present in stars with higher metals in their core than those which are metal deficient.
Small, rocky worlds should be more prevalent than big gas giants, as per core accretion. After millions of years, the solar wind of the young sun would have put away the entire gas and dust present in the protoplanetary disk blasting it into interstellar space and resulting in the growth of the planets coming to a halt.
13.3. Disk Instability
While other models find it difficult to interpret the way the gas giants formed, the disk instability model of planet formation overcomes this challenge.
Core accretion suggests that a few million years will be required for the process of the formation of gas giants which is much longer than the light gases which were present in the early solar system.
In this model, clusters of gas and dust are driven together and gradually compact into a giant planet. Scientists are continuing their study of planets inside of the solar system, and also around other stars to get a better understanding of the way the gas giants formed.
14. Nebula Hypothesis
How did the solar system form as per the Nebular hypothesis? The solar system formed as a result of the gravitational disintegration of a chunk of a massive molecular cloud. You can also find the modern variant of the nebular theory known as the solar nebular model, and this is the widely accepted model.
15. Evolution of the Planets
According to the Nice model, the giant planets were bound together more compactly in near-circular orbits when compared to our current scenario. When planets came into contact with smaller objects, it resulted in the scattering of the majority of these objects toward the sun.
This process resulted in the giant planets exchanging energy with smaller objects causing Saturn Uranus and Neptune to move further out into the solar system. Finally, the tiny objects upon reaching Jupiter were sent to the edge of the solar system or even entirely out of the same.
15.1. What Took Place Next?
Next, the movement between Jupiter and Saturn made Uranus and Neptune reach the rest of the Ice. Few materials were flung inward while the others were flung outward.
The material which was hurled inward smashed into the terrestrial planets at the time of the Late Heavy Bombardment, while those flung outward were responsible for the creation of the Kuiper belt.
16. Kuiper Belt
These are a region of icy bodies and you can find their shape resembling a donut and are found beyond Neptune’s orbit. You may find millions of these icy objects and together they are known as Kuiper belt objects.
This belt is the same as the asteroid belt. Want to know how? Because this belt is also a region of residue from the early history of our solar system.
Another similarity you can find between these two is that this belt has been shaped by a giant planet. However, its shape is of a thick disk instead of a thin belt.
17. Scattered Disk
This is the region that extends far away from the Kuiper belt’s main part. The objects that Neptune scatters into orbits find their place here.
Many objects’ orbits in the scattered disk are still developing, with objects becoming absent over time. Whereas, in the Kuiper belt, orbits remain very stable.
Though these two are considered separate regions according to a few astronomers, their boundaries overlay and find themselves interlinked in numerous ways.
Specifically, the objects present in these two regions are considered to have found their place there due to the relocation of Neptune from its initial closer orbit to its current position.
18. Late Heavy Bombardment
This event took place billions of years ago. During this event, the majority of asteroids as well as comets collided with planets including Mercury, Venus, Mars, and our very own planet Earth.
The Nice model suggests that the giant planets experienced an orbital migration that scattered objects from the Kuiper as well as the asteroid belt or might be even both into eccentric orbits.
19. How Our Planets Acquired Circular Orbits in the Formation of Planetary Systems
According to one of the hypotheses, gravitational drag took place between the planets and the rest of the small bodies rather than between the planets and lingering gas.
As the large bodies made their way through these crowded small bodies, the gravity of these larger ones pulled the smaller ones resulting in the formation of a gravitational wake in the path of the larger objects. In the process, the wake’s increased gravity decelerated the larger objects down into regular or circular orbits.
20. What Lies Ahead for Our Solar System?
According to astronomers, there will not be any drastic change in the present state of our solar system. However, this remains the same till our sun finally exhausts all its energy.
Once this happens, you can see the sun develop into a red giant star and will turn huge enough to consume the planets Mercury and Venus, and chances are likely that our planet earth may join the list too.
After this, the sun will be diminished to a white dwarf’s size, and the outer planets along with their moons will proceed to orbit this remaining sun.
21. How Will the Stability of Our Solar System Be?
This is a much-debated topic. This is because due to several examples, a planet’s position along its orbit cannot be predicted with confidence.
In a few cases, there are possibilities of changes in orbits too. Changes in eccentricity are the most visible indications of such chaos with the orbits of a few planets turning remarkably more or less elliptical.
Finally, our solar system is stable implying that there is no possibility for any of the planets to crash into each other or be forced out of the system any sooner.
21.1. What May Occur After This?
In the later years, which may even be in billions, the eccentricity of the planet Mars may increase in a manner that it stands in the path of an earth crossing orbit resulting in a possible collision. Subsequently, the eccentricity of the planet Mercury may increase even more and on coming closer in contact with Venus, theoretically, it can be expelled from our solar system totally or might collide with Venus or our own Earth.
Now, let us head on to another interesting section where you get to know some amazing facts about our planetary system, or the solar system and our only star – the sun.
22. Some Interesting Facts
- Our solar system comprises a star, eight planets as well as numerous smaller bodies namely the dwarf planets, comets, and asteroids.
- Our solar system needs approximately 230 million years to finish one orbit around the galactic center.
- Three types of galaxies are present in our solar system. They include elliptical, spiral, and irregular galaxies.
- Our solar system comprises a single star – our very own sun. Our solar system is also held together only by the gravity of the sun.
- The sun’s surface is not similar to the earth’s surface. While the earth has a solid surface, the sun is composed of electrically charged gas referred to as plasma.
How Many Moons Does Our Planet Earth Contain?
Our planet earth which we call our home has only one moon.
What Does Our Solar System Consist Of?
It comprises our sun, planets (eight), and tiny bodies namely asteroids as well as comets.
Getting to know about the formation of planetary systems is a topic that keeps you hooked. Scientists are still studying topics related to our solar system, and soon we can expect some fascinating discoveries.