The Chamberlin–Moulton planetesimal hypothesis is another name for the Planetesimal Hypothesis which was proposed by Thomas Chamberlin and Forest Moulton in 1905. According to this hypothesis, the Solar System's planets were thought to have formed from a collision between the Sun and another star. This is an important theory to understand the formation of the Solar System as per the UPSC syllabus. In this article, you will read about the Chamberlin-Moulton planetesimal hypothesis in detail for the IAS exam.

Chamberlin-Moulton planetesimal

What exactly is Chamberlin-Moulton Planetesimal Hypothesis?

• Chamberlin–Moulton stated that the Solar System's planets had formed as a result of a collision between the Sun and another star.
• In this scenario, the gravity of the passing star shredded a series of bolts from the solar surface.
• Bolts ejected from the Sun's near side were thrown out to distances comparable to those of the big planets. Bolts ejected from the Sun's far side are ejected less forcefully to distances comparable to those of the terrestrial planets.
• The planets' original cores were produced from the inner leftovers of these bolts.
• The outer parts expanded and cooled into a massive swarm of solid particles that strewn across a disc moving around the Sun in a plane specified by the passing star's speed.
• The cores gradually developed into planets by accumulating in planetesimals, with the majority of the expansion taking place in the Solar System's outer parts, where the material was more abundant.

Merits of Planetesimal Hypothesis

• The planetesimal theory explains the formation of meteorites and meteor showers.
• It also explains the highly elliptical orbits of small planetary bodies, and almost circular orbits of larger things.

Criticism of Planetesimal Hypothesis

• Failure to explain the massive passing stars, which must remain near the Sun.
• The stars in space are so far apart, that moving from one to the next is impossible.
• It was not able to explain the existence of only eight planets.
• Also, this hypothesis was not able to explain the different dimensions of planets.

Conclusion

The Planetesimal theory explains the origin of the earth's various constituent parts. It also suggests Planetesimal matter was initially added at a rapid rate, but afterward at a slower rate. Production of internal heat was also explained by the condensing of its mass throughout the growing period. It is opposed to the concept of a molten earth. Despite several criticisms, the Planetesimal theory's essential idea has been accepted.

FAQs

Q1: What is the Chamberlin-Moulton Planetesimal Hypothesis?

Q2: How does the Planetesimal Hypothesis differ from the Nebular Hypothesis?

Q3: What role do planetesimals play in the formation of planets according to the Chamberlin-Moulton Hypothesis?

Q4: How were the planetesimals formed according to the hypothesis?

Q5: Why is the Chamberlin-Moulton Hypothesis considered an alternative to other solar system formation theories?

MCQs

1. According to the Chamberlin-Moulton Hypothesis, planets were formed through which of the following processes?

A. Condensation of gases

B. Accretion of planetesimals

C. Explosion of a supernova

D. Cooling of a molten star

2. The planetesimals in the Chamberlin-Moulton Hypothesis were formed as a result of:

A. A supernova explosion

B. The gravitational pull of a nearby passing star

C. The rotation of the solar nebula

D. The cooling of the Earth's surface

3. What does the Chamberlin-Moulton Hypothesis propose about the formation of the solar system?

A. The solar system was formed from a collapsing nebula

B. The planets formed from planetesimals after a stellar encounter

C. The planets formed from cooling gas

D. The planets were ejected from the sun during a supernova explosion

4. Which of the following is NOT a feature of the Chamberlin-Moulton Hypothesis?

A. Planetesimal aggregation

B. Accretion of small bodies

C. Formation from a passing star

D. Direct formation from a gas cloud

5. The Chamberlin-Moulton Hypothesis was proposed as an alternative to which solar system formation theory?

A. Giant Impact Hypothesis

B. Nebular Hypothesis

C. Fission Theory

D. Capture Theory

GS Mains Questions and Model Answers

Q1: Discuss the significance of the Chamberlin-Moulton Planetesimal Hypothesis in the study of the origin of the solar system.

Answer: The Chamberlin-Moulton Planetesimal Hypothesis is significant because it provides an alternative explanation for the formation of the solar system, focusing on the role of planetesimals rather than the condensation of gas. This hypothesis suggests that a passing star caused material to be ejected from the sun, which later coalesced into solid bodies known as planetesimals. These planetesimals collided and merged over time to form the planets. The hypothesis helped address some of the shortcomings of the Nebular Hypothesis by providing a more detailed mechanism for the formation of solid bodies in the solar system.

Q2: Explain the process of accretion in the context of the Chamberlin-Moulton Planetesimal Hypothesis.

Answer: In the Chamberlin-Moulton Planetesimal Hypothesis, accretion refers to the process by which planetesimals (small solid bodies) collide and merge to form larger celestial bodies such as planets and moons. Following the ejection of material from the sun due to a passing star, planetesimals formed and began to attract each other through gravitational forces. As these objects collided, they stuck together, growing in size and mass. Over millions of years, this process led to the formation of the planets in the solar system.

Q3: Compare the Chamberlin-Moulton Planetesimal Hypothesis with the Nebular Hypothesis in terms of their explanations for planetary formation.

Answer: The Nebular Hypothesis suggests that the solar system formed from a rotating cloud of gas and dust, with planets condensing directly from the gas. In contrast, the Chamberlin-Moulton Planetesimal Hypothesis proposes that planets formed from planetesimals, which were solid objects created after a close encounter between the sun and a passing star. The planetesimals collided and merged to form planets over time. While both hypotheses aim to explain the origin of the solar system, the Nebular Hypothesis focuses on gas condensation, while the Planetesimal Hypothesis emphasizes the role of solid bodies and gravitational accretion.

Previous Year Questions on Chamberlin-Moulton Planetesimal Hypothesis

1. UPSC CSE Prelims 2020

Question: Which of the following theories proposes that planets were formed through the aggregation of planetesimals?
A. Nebular Hypothesis
B. Fission Theory
C. Chamberlin-Moulton Planetesimal Hypothesis
D. Capture Theory

Answer: C

Explanation: The Chamberlin-Moulton Planetesimal Hypothesis proposes that planets were formed through the aggregation of planetesimals after a stellar encounter.

2. UPSC CSE Mains 2019 (GS Paper 1)

Question: Discuss the importance of alternative hypotheses like the Chamberlin-Moulton Planetesimal Hypothesis in advancing our understanding of planetary formation.

Answer: Alternative hypotheses like the Chamberlin-Moulton Planetesimal Hypothesis play a crucial role in advancing our understanding of planetary formation by offering different perspectives on how planets came into existence. This hypothesis challenges the traditional Nebular Hypothesis by focusing on the role of planetesimals—small solid bodies formed after a stellar encounter—in the formation of planets. By providing a detailed mechanism for the accretion of solid bodies, the Planetesimal Hypothesis enhances our understanding of the complex processes involved in the formation of the solar system and highlights the importance of considering multiple explanations for natural phenomena.