The Origin and Evolution of the Earth

Overview

This chapter examines the birth of the universe and our planet. It covers early hypotheses like the Nebular Hypothesis and the modern Big Bang theory, detailing the transformation of a primordial Earth into a layered, life-supporting planet.

Learning Objectives

Explain the Big Bang theory's sequence and evidence
Describe the process of star and planet formation
Analyze the differentiation of Earth's internal layers
Trace the evolution of the atmosphere and hydrosphere

Key Concepts

The Big Bang Theory

Also known as the expanding universe hypothesis. It suggests the universe began around 13.8 billion years ago from a tiny 'singularity' and has been expanding and cooling ever since.

Planetary Differentiation

As early Earth melted due to heat from impacts and radioactive decay, heavier elements (Iron/Nickel) sank to form the core, while lighter silicates rose, creating a layered structure.

Key Terms

RedshiftAccretionOutgassingPlanetesimalsZircon

Examples

Edwin Hubble’s Observation

Hubble observed that galaxies move away from us at speeds proportional to their distance, providing key evidence for the Big Bang.

Quick Check

How old is the Earth?
What is 'outgassing'?