Earth’s System: The Story of How Our Planet Was Born

1. What is earth system? 2. How our earth formed? 3. Nebular Hypothesis

D isaster Science & Management-Welcome to DSM-BD. Our mission is to bridge the gap between disaster science theory and practical management to safeguard communities across Bangladesh. This hub is for students, researchers, and practitioners committed to making a difference. Let's build a safer future, together.

Introduction — Earth’s Long Journey

The Earth we live on, with blue oceans, green forests, and millions of living creatures, was not always like this. About 4.54 billion years ago, there was no Earth — only a huge cloud of gas and dust floating in space. Over millions of years, that cloud turned into our planet. This story is called the origin of Earth. By studying it, scientists understand how life became possible here and how Earth’s systems work today.

1. How the Earth Formed — Step by Step

The most accepted theory for the Earth’s birth is the Nebular Hypothesis. It says our planet formed from a giant cloud of gas and dust in space.

Here’s how it happened:

The Solar Nebula
- Around 4.6 billion years ago, a massive cloud of gas and dust (mostly hydrogen and helium) floated in space.
- Then something — maybe a nearby star exploding (a supernova) — disturbed it.
Gravity Took Control
- Gravity pulled the cloud together.
- It started spinning and flattened into a disk.
- Most of the mass collected in the center and became the Sun.
Small Particles Became Big Rocks
- The leftover dust stuck together, forming small lumps called planetesimals.
- Over time, they crashed into each other and grew into bigger bodies called protoplanets.
Birth of the Early Earth
- One of these protoplanets became Earth.
- At first, it was very hot, molten, and constantly hit by asteroids.
Cooling and Formation of the Crust
- Slowly, Earth’s surface cooled and hardened.
- Volcanic eruptions released gases — forming the early atmosphere.
Water and Oceans Appear

Water vapor from volcanoes condensed into rain.
Rain filled low areas, creating the first oceans.
Comets that hit Earth may have also brought extra water.

2. The Beginning — Nebular Hypothesis

The most widely accepted explanation for Earth’s origin is the Nebular Hypothesis.

Here’s the story in simple steps:

A Cloud of Gas and Dust
Long ago, the Solar System was just a huge cloud made of hydrogen, helium, and other tiny particles.
Gravity Pulled It Together
Gravity caused the cloud to collapse, spinning and flattening into a disk. Most of the material gathered at the center to form the Sun.
Tiny Particles Became Big Rocks
Dust particles in the disk stuck together to form small lumps, then bigger rocks called planetesimals.
Formation of the Earth
Over millions of years, these planetesimals collided and merged, becoming the early Earth — a hot, molten ball.
Cooling and Crust Formation
As Earth cooled, a solid crust formed, volcanic gases created an early atmosphere, and water vapor led to the first oceans.

3. Early Earth — A Very Different Place

If we could time travel to early Earth, we wouldn’t survive without a spacesuit!

The atmosphere had no oxygen — it was full of carbon dioxide, nitrogen, and methane.
The ground was covered with volcanoes and lava flows.
Oceans were hot, and the sky was dark with thick clouds.

Example: Imagine a mix between a boiling pot of water, a thunderstorm, and a volcano eruption — that’s what early Earth was like.

4. How Earth’s Systems Developed

Over millions of years, Earth became more stable and developed four major systems:

Geosphere – Rocks, mountains, soil, and the inner layers of Earth.
Example: Plate tectonics forming continents.
Hydrosphere – All the water on Earth (oceans, rivers, lakes, ice).
Example: The water cycle keeping rivers flowing.
Atmosphere – The blanket of air that protects us.
Example: Ozone layer blocking harmful Sun rays.
Biosphere – All living things: plants, animals, humans.
Example: Coral reefs, forests, grasslands.

These systems are always connected — a change in one can affect the others.

5. Why Studying Earth’s Origin is Important

To understand our planet’s history — and how it became habitable.
To predict the future — knowing past climate and geology helps forecast changes.
To search for life on other planets — by comparing their formation to Earth’s.
To protect the environment — realizing how rare and fragile our planet is.

6. Fun Facts About Earth’s Formation

The Moon was likely formed when a Mars-sized body hit early Earth, sending debris into space that later joined to form the Moon.
Early Earth days were only 6 hours long because it spun much faster.
The first life may have appeared in oceans 3.5–3.8 billion years ago.

Books & References

The Earth: Its Origin, History and Physical Constitution – Harold Jeffreys
The Origin of the Earth – G.P. Kuiper
Earth Science – Edward J. Tarbuck & Frederick K. Lutgens
NASA Solar System Exploration Archives
USGS (United States Geological Survey) – Earth’s Formation Studies

Related Terms

Earth Science Origin of Earth Earth formation Earth’s system history of the Earth solar system origin

Written By

Mr. Mehedi Hasan

Master of Biochemical Engineering & Technology, SIIT, Thammasat University, Thailand

Research Assistant, SIIT, Thammasat University, Thailand

Bachelor of Science, Disaster Science & Management, BRUR, Bangladesh

Authenticity Information

Peer-Reviewed & Fact-Checked

Reviewed by: Dr. B. Kaur

Published & Attested

Published On: August 10, 2025

M. Hasan

- Official Attestation -

Our page was last updated on 10/08/2025. You have accepted our Terms and Conditions.