Formation of Star, Planet and Solar System

The Sun and the planets originated together 4.6 billion years ago from the solar nebula, a cloud of gas and dust. The collapse of the solar nebula was most likely caused by a shock wave from a nearby supernova explosion. In the centre, the Sun formed, and the planets formed in a narrow disc encircling it. In geography class 11: formation of a star, planet, and solar system notes, we will discuss the formation of stars, formation of planets, the solar system, types of planets, and theories related to the moon’s origin. 

Formation of Stars 

• According to NASA’s Wilkinson Microwave Anisotropy Probe (2003), stars began to form when the universe was 200 million years old. The same probe observed that the universe is 13.7 billion years old
• A nebula is a very large cloud of accumulated hydrogen. It is believed that as the nebula grew in size, localized lumps started to develop. These localized lumps grew into denser gaseous bodies, which would later be converted into stars
• It is believed that when the universe was forming, there was an uneven distribution of matter and energy, which drew matter together

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Formation of planets 

The formation of planets is widely divided into three stages.  

First stage

• Localised lumps of gases within a nebula converted into stars

• The core of the stars has a gravitational force which leads to the formation of a gas cloud around a rotating disc of gas. Dust also starts to develop around the star’s core

Second Stage

• As time passes, the gas cloud begins to condense, and the dust/matter that has developed around the core starts to form into a small round object. The small round objects are called planetesimals

• The gravitational force of such planetesimals starts to attract large bodies, which collide and stick together to form a larger object

Third Stage

• Through the process of accretion, the planetesimals stick together to form a planet
• To define accretion, it is the process through which gas and dust are gathered together by gravitational forces. The majority of cosmic objects, such as galaxies, stars, and planets, are produced via the process of accretion

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Types of Planets 

Inner Planets

• Inner planets are smaller, higher in density, have a solid rocky state, and are generally warmer within our solar system
• Mercury, Venus, Earth, and Mars are known as terrestrial planets or inner planets
• Terrestrial or inner planets are found between the sun and the belt of asteroids

Outer Planets

• Jovian or outer planets refer to the planets that are found beyond the asteroid belt
• Outer planets are bigger, have low density, cold, and are gaseous in the state
• Jupiter, Saturn, Uranus, and Neptune are outer planets

Reasons for the differences between Terrestrial and Jovian planets

• Location-While terrestrial planets are closer to the sun, Jovian planets are further away from it

• Size- Terrestrial planets are smaller

• Solar Winds- Solar winds are more intense in terrestrial planets

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The Solar System 

• The solar system is composed of the sun, eight planets, 63 moons, huge quantities of dust grains and gases, and millions of asteroids and comets
• To explain what asteroids are, these are tiny irregularly shaped objects composed of rock, metal, and carbon that circle the sun. The asteroid belt contains the majority of these objects, which are located between the orbits of Mars and Jupiter
• Originally, the solar system included nine planets; however, scientists subsequently revealed Pluto as an ice body, reducing the number of planets in the solar system to eight
• The solar system was formed from a nebula that collapsed around 5-6 billion years ago
• The planets within the solar system started to form at least 4.6 billion years ago

Theories related to the origin of the moon  

• Sir George Darwin, in 1838, propounded that the earth and the moon formed a single rotating body that was dumbbell-shaped. This theory also suggested that the moon was separated from the earth from the Pacific Ocean
• Another theory related to the moon’s origin suggested that a body three times the size of Mars collided with earth also known as the big splat and launched a large part of Earth back into space. This blasted-off portion would eventually form into the moon about 4.44 billion years ago 

Conclusion

Conclusively, we looked into the solar system and its components such as the sun, stars and the moon. We can say that the solar system is massive, and it is kept together by the sun’s enormous gravitational attraction, which maintains planets and asteroids in orbit around it. Moreover, The sun is the most gigantic object in the solar system.