The Origin and Evolution of the Earth (Part II & III)

Earth's Formation and Evolution

• The process of differentiation involves the separation of Earth's inner layers into a core, mantle, and crust.
• The Big Bang Theory marks the beginning of the universe, with the exact event unknown.
• The primary source of oxygen in the early Earth's atmosphere was oxygen-producing cyanobacteria.
• The estimated age of the Earth is approximately 4.5 billion years according to scientific calculations.
• Life first appeared on Earth during the Hadean geological era.

Atmospheric Transformation

• The process of oxygenation transformed the early Earth's atmosphere into an oxygen-rich environment.
• Small-rounded objects that develop from the matter surrounding the core in the formation of planets are called planetesimals.

Planet Formation

• Gravity causes the material to stick together after larger bodies start forming by collision during planet formation.
• The atmospheric gases present when the planet Earth was initially a barren, rocky, and hot object were hydrogen, helium, and methane.
• The process of planetary accretion led to the change from a barren, hot Earth to a planet with water and a conducive atmosphere for life.

Evolution of Life

• The period of evolution of life on Earth's surface encompasses approximately 4 billion years.
• The term accretion best describes the smaller bodies that accrete to form fewer large bodies, such as planets, in the final stage of planet formation.

Nebular Hypothesis

• The Nebular Hypothesis proposes that planets formed from a cloud of gas and dust called the solar nebula.
• Pierre-Simon Laplace revised Immanuel Kant's argument about the origin of the Earth.
• In 1950, scientists Harold Urey and Alfred E. Ringwood revised the Nebular Hypothesis.
• German scientist Viktor Safronov contributed to revising the Nebular Hypothesis.
• Laplace's role was to propose the Nebular Hypothesis, which suggests that planets formed from a cloud of gas and dust called the solar nebula.

Explore the process of how the Earth originated and evolved according to Rationalised-2023-24 15. Learn about the formation of planetesimals and how larger bodies formed through collision and gravitational attraction.