Evolution of Earth

How did the earth come into existence? What is the origin of the Earth? How did the Evolution of Earth happen? Several studies were conducted to find out about the evolution of Earth. However, there are two famous theories about the same. The first theory is the core accretion model and the second theory is the disk instability method. These theories are merged with the pebble accretion theory. 

Origin of the Earth

Around 4.5 billion years ago, an unrecognised explosion by a distant star caused a disturbance in the cloud of gas and dust, resulting in pulling them together. This pull created a spinning disc of dust and gas called the solar nebula, along with gravity it began to spin and formed the sun in the centre of the nebula. The remaining material clumps up and is bound together by gravity into large particles. When the lighter materials were swept away by the solar storm, the heavy materials formed the planets and other celestial bodies. Several million years later, the outer crust of the Earth was formed.

Evolution of Earth

The evolution of the earth started with the suffering of the earth with an impact caused by the catapulted pieces of the young planet’s mantle into space. With the gravitational pull many of the young planets held together to form the moon that took up the orbit around the earth. The mantle beneath the crust of the earth causes tectonic plates moments, resulting in the movement on the surface of the earth. These friction and collisions gave rise to volcanoes and mountains that spew gases.

During the formation of the Earth it didn’t have any atmosphere. The atmosphere began to form with the cooling of the planet and the gases captured from the volcanoes on the Earth due to gravity. During the early time of the formation of planets and sun, the comets and asteroids were abandoned and the collision between them caused the deposition of water on the surface of the earth.

Different Stages of the Earth

According to the different theories by the scientists, the Terrestrial planets like earth were formed by flogging together from the gas and dust into the hot blocks of Rock and Molten metals. After becoming a planet, the Earth went through the different stages of formation. There were four different stages in the formation of the earth. They are as follows:

1.Differentiation: At this stage the Earth or a body became large enough to attract the planetesimals (solid objects that are theorised to have coalesced to form the planets) and become a planet. These frequent impacts caused the generation of energy which began the process of differentiation. 

In this process, the dense material moved towards the core of the earth while the fine material formed the atmosphere and crust of the earth. This process happened due to minimization of gravitational energy by the system.

2. Cratering: The bombardment of planetesimals continued even after the cooling of the planet’s crust. As the planet or Earth was no longer in the form of molten, however the bombardment of planetesimals impacts created craters. In the early stages, the number of impacts were high and to prove this theory, there is evidence that the moon and mercury have been saturated with craters since the formation.

3. Flooding: As the cratering continued, with the result of these, the crust of the planet fractured, which caused the burst of lava from the planet, which flowed over the land and smoothened these craters. 

In the case of the Earth, apart from lava, water vapour also flooded through these fissures. The water vapour rose into the atmosphere and fell to the ground. This phenomenon is known as rain that formed water bodies like the ocean and rivers on the earth.

4. Surface Evolution: This is the last stage of formation of the planet which lasted for a billion years. In this stage, the planet’s surface is altered by the movement of atmosphere, tectonic plates, and water. The movement of tectonic plates caused collisions that pushed up the mountains, which shifted the continents. 

The wind and the rain slowly wore away the surfaces and removed all the evidence of early stages of planet formation. In the case of Earth, these activities caused the Earth to become hotter than before (at the time of formation), which might be the reason for the evolution of life on the Earth.

Timeline of the Evolution of the Earth

• 4.6 Billions years ago – Formation of the planet.
• 4.5 Billions years ago – Formation of the core and crust of the earth.
• 4.4 Billions years ago – Formation of the first ocean on the earth.
• 3.85 Billions years ago – Appearance of the first life on the earth.
• 1.5 Billions years ago – Accumulation of the oxygen in the earth’s atmosphere
• 700 millions years ago – Evolution of single celled animal
• 530 millions years ago – Evolution of the first fish.
• 400 millions years ago – Evolution of the first land plants
• 350 millions years ago – Evolution of the first land vertebrates
• 225 millions years ago – Evolution of the first dinosaurs from lizards
• 65 millions years ago – Extinction of the dinosaurs. 
• 0.13 millions years ago – Evolution of Modern humans. 

Conclusion

In the above article, a study on the evolution of Earth, we have started with the origin of the earth and continue on the evolution of the earth along with the other related topics. To wrap up the article for easy understanding we have mentioned the timeline of the evolution of the earth.