---
title: "Nebular hypothesis"
subject: "Engineering Geology I"
chapter: 2
key: "semester_3/engineering_geology_i:nebular-hypothesis"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/nebular-hypothesis
site: BCT Engineering
---

# Nebular hypothesis

Engineering Geology I · Chapter 2: Basic Reviews of the Earth

- Asked in: 2081 Baisakh (new course), 2 marks
- Video: [Nebular Hypothesis](https://www.youtube.com/watch?v=fuA_m-lBhNo) — Earth Explained
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/nebular-hypothesis
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-2

## Question

Discuss the nebular hypothesis for the origin of the earth.

## Short answer

Kant and LaPlace proposed the solar system originated from a rotating nebular cloud that contracted, flattened into a disk, and shed rings which condensed into planets. The central mass formed the Sun. The hypothesis fails to account for the Sun's low angular momentum and retrograde satellite orbits.

## Answer

The **nebular hypothesis** was proposed by Immanuel Kant (1755) and developed by Laplace (1796).

- The solar system began as a huge, hot, rotating cloud of gas and dust called a nebula.
- As it cooled, it contracted and, to conserve angular momentum, rotated faster and flattened into a disc.
- When the centrifugal force at the edge equalled gravity, a ring of gas was thrown off. This repeated several times, forming rings.
- Each ring condensed into a planet; the central mass became the Sun. Rings around planets formed satellites.
- The Earth cooled from a hot gaseous ball into a liquid and then formed a solid crust.

Limitation: it cannot explain why the Sun has only 2% of the angular momentum of the solar system, or why some satellites move backwards.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Nebular hypothesis was proposed by:
   A. Jeans and Jeffreys
   B. Wegener
   C. Hess
   D. Kant and Laplace
   Answer: D. Tidal is Jeans and Jeffreys. (Key point: Proposers)

2. Planets formed when:
   A. Rings thrown off the spinning nebula condensed
   B. A star passed the Sun
   C. Meteors collided
   D. Sun exploded
   Answer: A. Ring condensation. (Key point: Mechanism)

3. A limitation is:
   A. Cannot explain rotation
   B. Cannot explain Sun's low share of angular momentum
   C. Needs a passing star
   D. Ignores gas
   Answer: B. Sun has only 2%. (Key point: Limitation)

## Related in Engineering Geology I

- [Tidal hypothesis](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atidal-hypothesis) — Engineering Geology I, chapter 2