Theories of Planet Formation Questioned Reading Answers

Jul 1, 2025

Theories of Planet Formation Questioned Reading Answers consists of 14 questions to be answered within 10 minutes. It is an IELTS reading answer topic. The topic: Theories of Planet Formation Questioned Reading Answers is the first part of the reading section. It contains questions such as choosing which paragraph A-I contains the given statement, complete each sentence with the correct ending, A-G, and complete the summary using the list of words, A-F. The candidates must examine the IELTS reading passage for keywords. The candidates must analyse each line of the passage attentively to give answers to the questions. The topic: Theories of Planet Formation Questioned Reading Answers tests the reading and analysis skills of the candidates. It can help candidates get accustomed to different question formats in reading tasks, improve their vocabulary, and enhance their critical reading abilities. The candidates must go through IELTS reading practice papers to become familiar with similar topics.

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Section 1 THEORIES OF PLANET FORMATION QUESTIONED

A. The traditional view of astronomy has been that planets form slowly as material congeals within the disk of gas, dust, and ice known to surround young stars. First, gravity gathers together bits of dust that merge to form boulder-sized bodies, which themselves coalesce into

bigger and bigger objects. In about a million years, these form rocky planets like Earth and Mars. Over the next few million years, gas from the disk settles around some of these solid bodies, and they grow far larger, becoming giants like gaseous Saturn and Jupiter. This theory

of planet formation is known as the core-accretion model. However, several astronomers now say that this model for making planets may not be entirely correct.

B. These astronomers have devised an alternative theory in which planets as massive as Jupiter, whether orbiting our sun or a distant star, would form completely within a few hundred years, rather than millions of years as previously believed. Both theories for planet formation

start with the same reservoir of planet-making materials. The spinning cloud of gas, dust, and ice rapidly fattens into disk-like shapes known as proto-planetary disks; and, as time goes by, gravity causes material in these disks to clump into planet-sized objects. However, it is the

speed of the clustering, and the size of the initial clumps, that provide the disparity in the two models for planet formation.

C. According to the core-accretion model, the making of Jupiter required the initial formation of a solid core five to ten times Earth's mass. It would have taken about a million years to achieve this. Most astronomers believe that the large core then had enough gravity to attract a huge amount of gas from the proto-planetary disk to create a planet of the massive proportions of Jupiter. In this core-accretion model, these 'gas giants' may take as long as ten million years to form.

D. That is several million years too long in the opinion of Lucio Mayer of Zurich University. Direct telescope sightings suggest that the proto-planetary disks do not last more than about seven million years, and studies of the environment in which stars form suggest that many disks may evaporate in much less time. Mayer asserts that most stars in the Milky Way form in dense clouds of gas, dust, and ice. Their temperatures are very intense, and the ultraviolet light they send into space can evaporate a proto-planetary disk in less than 100,000 years. In the core-accretion model, that is not enough time for a Jupiter-like planet to form.

E. Recent computer simulations show that when individual stars form, the gravitational pull between them can result in the outer gaseous parts of the proto-planetary disks being destroyed in 100,000 years or less. Thus, Thomas Quinn of the University of Washington concludes that if a gas giant planet cannot form quickly, it will probably never form. He also asserts that if the core-accretion model is correct, gas giant planets like Jupiter should be rare. However, since 1995, astronomers have found more than one hundred planets as large as Jupiter

outside our solar system.

F. Quinn and his colleagues recently analysed the standard core-accretion model of planet formation and investigated whether giant planets could form quickly. They looked at the work of Gerard Kuiper, who, in the 1950s, proposed that they could. Alan P. Boss of the Carnegie Institute did more extensive work on the subject in the late 1980s. Using computer simulations, he was surprised to find that gravity could cause a proto-planetary disk, after a few orbits of its parent star, to break into clumps as big as an average-sized planet. The clumps would continue to pull in gas, ice, and dust. This is called the gravitational-instability model of planet formation.

G. Recent calculations have suggested that many of the solid bodies that might be the rocky core for Jupiter-size planets in the traditional theory would pin into the parent star before the massive planet could form. Moreover, further analysis has shown that other effects could

also cause a proto-planetary disk to become unstable and split into large fragments. For instance, within the disk, electrically charged material might accumulate, leading to fragmentation of the disk. Or a powerful gravitational disturbance, such as the pull of a star passing nearby, could produce instability in the proto-planetary disk.

H. Nevertheless, the gravitational-instability model has problems of its own, as it is mathematically complicated and requires sophisticated computer use. Therefore, no one has studied the simulations long enough to establish conclusively that the model allows for the formation of massive planets.

I. In response, Mayer says that he and his team have described the results of an extensive simulation based on the gravitational-instability model. They spent two years refining calculations to track what would happen to a proto-planetary disk over one thousand years, which is more than any other simulation had done. In addition, over a decade previously, Mayer and his team had made simulations of the formation and evolution of galaxies. In doing this, they had already developed a fast computer code that could run in parallel on machines with hundreds of processors, and this knowledge assisted them in investigating their gravitational-instability theory.

Questions 27-32

Reading Passage 3 has nine paragraphs, A-I. Which paragraph contains the following information? Write the correct letter, A-I.

27. The significance of recent discoveries of a large number of massive planets

Answer: F

Supporting statement: planet formation and investigated whether giant planets could form quickly.

Keywords: investigated, giant planets

Keyword Location: Para F, Line 2

Explanation: Paragraph F contains information about the recent discoveries about planet formation, and the possibilities of giant planets forming quickly were also investigated.

28. An explanation of the difference between the theories of planet creation

Answer: B

Supporting statement: would form completely within a few hundred years, rather than millions of years as previously believed

Keywords: hundred, years

Keyword Location: Para B, Lines 2-3

Explanation: Paragraph B contains a detailed explanation regarding the different theories of planet creation, such as the previously proposed creation theory of Jupiter, which was believed to have taken a million years to form, but now it is believed that it might have taken only a few hundred years to form.

29. The difficulties of proving that the more recent theory of planet creation is correct

Answer: H

Supporting statement: the gravitational-instability model has problems of its own, as it is mathematically complicated and requires sophisticated computer use.

Keywords: gravitational-instability, complicated

Keyword Location: Para H, Lines 1-2

Explanation: Paragraph H mentions the difficulty in proving the recent theory of planet creation using the gravitational-instability model, as it has many issues associated with it.

30. Reasons why Mayer claims he was able to develop his theory

Answer: I

Supporting statement: they had already developed a fast computer code that could run in parallel on machines with hundreds of processors,

Keywords: developed, computer code

Keyword Location: Para I, Line 6

Explanation: In Paragraph I, Lucio Mayer claimed that he was able to develop the theory with the help of the already developed fast computer code, which was able to run in parallel on machines with hundreds of processors.

31. A detailed explanation of the long-held theory of planet creation

Answer: A

Supporting statement: First, gravity gathers together bits of dust that merge to form boulder-sized bodies, which themselves coalesce into bigger and bigger objects.

Keywords: boulder-sized, bigger

Keyword Location: Para A, Line 3

Explanation: Paragraph A contains a thorough justification of the long-held belief that planets develop gradually when material solidifies inside the disk of gas, dust, and ice that surrounds newborn stars.

32. Description of the destructive effect of heat in space

Answer: D

Supporting statement: Their temperatures are very intense, and the ultraviolet light they send into space can evaporate a proto-planetary disk

Keywords: temperatures, ultraviolet light

Keyword Location: Para D, Line 5

Explanation: Paragraph D mentions that heat in space and Ultraviolet light can make a proto-planetary disk evaporate easily.

Questions 33-37

Complete each sentence with the correct ending, A-G.

33. Traditionally, astronomers have believed that….

Answer: B

Supporting statement: Jupiter, whether orbiting our sun or a distant star, would form completely within a few hundred years, rather than millions of years as previously believed.

Keywords: Jupiter, millions

Keyword Location: Para B, Lines 2-3

Explanation: According to astronomers, it is believed that giant gas planets form before rocky small planets. For example, Jupiter might have formed a few million years before a small rocky planet such as the Earth.

34. LUCIO MAYER physically observed that...

Answer: F

Supporting statement: and studies of the environment in which stars form suggest that many disks may evaporate in much less time.

Keywords: environment, less time

Keyword Location: Para F, Line 3

Explanation: According to Lucio Mayer of Zurich University, his telescope observations indicate that the proto-planetary disks have a lifespan of little more than seven million years, and research on the star-forming environment indicates that many disks might disappear much faster.

35. THOMAS QUINN believes that...

Answer: C

Supporting statement: Thus, Thomas Quinn of the University of Washington concludes that if a gas giant planet cannot form quickly, it will probably never form.

Keywords: Thomas Quinn, gas giant

Keyword Location: Para E, Lines 3-4

Explanation: Thomas Quinn of the University of Washington states that a giant gas planet will never form if it does not form quickly.

36. GERARD KUIPER was the first to suggest that...

Answer: D

Supporting statement: They looked at the work of Gerard Kuiper, who, in the 1950s, proposed that they could

Keywords: Gerard Kuiper, 1950s

Keyword Location: Para F, Line 3

Explanation: According to the passage, it was Gerard Kuiper who proposed the theory that large planets developed a lot faster than smaller planets in 1950.

37. ALAN P. BOSS discovered that...

Answer: E

Supporting statement: to break into clumps as big as an average-sized planet.

Keywords: clumps, planet

Keyword Location: Para F, Line 6

Explanation: A proto-planetary disk may break into lumps as large as an average-sized planet after a few revolutions of its parent star due to gravity, according to the comprehensive study done in the late 1980s by Alan P. Boss of the Carnegie Institution.

A. Large planets take millions of years to form.

B. Gaseous planets form before smaller rocky planets.

C. Large planets must form fast or not at all.

D. Large planets had the potential to develop relatively fast.

E. Gravity could cause planet-sized pieces to break off quickly.

F. Hot clumps of gas, dust, and ice were destroyed relatively quickly.

G. Computer studies of planets are too mathematically complex.

Questions 38-40 Complete the summary using the list of words, A-F.

THE CORE-ACCRETION MODEL

A hard centre becomes larger, and this produces enough gravity to draw gas from the 38………. around it.

Answer: F

Supporting statement: Over the next few million years, gas from the disk settles around some of these solid bodies,

Keywords: disk, solid bodies

Keyword Location: Para A, Line 5

Explanation: According to the text, some of these solid bodies gradually evolve into giants like gaseous Jupiter and Saturn as gas from the disk settles around them over the following few million years.

THE GRAVITATIONAL INSTABILITY MODEL

Stars can break up the outer gaseous parts which surround objects in the sky because the attraction of the 39………..from stars is very powerful.

Answer: A

Supporting statement: Recent computer simulations show that when individual stars form, the gravitational pull between them can result in the outer gaseous parts of the proto-planetary disks

Keywords: gravitational pull, outer gaseous

Keyword Location: Para E, Line 1

Explanation: According to the passage, because of their strong gravitational pull, stars can disintegrate the outer gaseous regions that encircle heavenly bodies.

Heat caused by 40………. can also destroy the material surrounding the objects in a relatively short time. Planet-sized segments may split away from the main body following several orbits of the parent Star.

Answer: D

Supporting statement: Their temperatures are very intense, and the ultraviolet light they send into space can evaporate a proto-planetary disk in less than 100,000 years.

Keywords: ultraviolet light, proto-planetary disk

Keyword Location: Para D, Lines 5-6

Explanation: As per the text, Higher temperatures in space caused by the ultraviolet light can cause a proto-planetary disk to evaporate in a very short time.

A. Gravitational pull

B. Ice

C. Solid core

D. Ultraviolet light

E. Milky Way

F. Disk

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