In The Early 1900s, Most Astronomers Mistakenly Believed GMAT Reading Comprehension

Reading Passage Question

In the early 1900s, most astronomers mistakenly believed that 66 percent of the sun’s substance was iron. As a graduate student at Harvard University in the 1920s, Cecilia Payne—later a professor of astronomy there—argued pioneeringly that the sun is instead composed largely of hydrogen and helium. Her claim, though substantiated by the evidence and later uniformly accepted, encountered strong resistance among professional astronomers.

The orthodox view that the sun was mainly iron was buttressed by the knowledge that Earth and all known asteroids contain iron. Also, the evidence from spectroscopy—a technique used to identify chemicals by the distinctive spectral properties of the light patterns they emit when heated to incandescence—was generally taken to show that iron was the predominant element in the sun. But how could a body composed largely of iron generate the huge energy output of the sun? The eminent British physicist Lord Kelvin had hypothesized that the sun was continuously contracting and that the resulting compression had raised the temperature of the sun’s materials sufficiently to account for its enormous heat. But, given the usual assumptions about the sun’s size and rate of contraction, it followed that the sun’s age would be about 20 million years; evidence from the fossil record, however, strongly suggested that the sun had warmed Earth for billions of years. For Payne, this meant that the “iron” hypothesis had to be reexamined, together with the extensive spectroscopic data alleged to support it.

Preliminary examination of the spectroscopic data convinced Payne that they lent themselves to multiple readings. She suspected that preconceptions about the sun’s makeup as being mainly iron might have led to skewed interpretations of that data, and this led her to subject the data to rigorous critical scrutiny and review. Analyzed without preconceptions, she found, the data could be consistently read as indicating that, while it does indeed contain iron (along with other elements found on Earth), 90 percent of the sun is hydrogen and most of the remainder is helium. Most astronomers at the time dismissed Payne’s interpretation, and some sought to explain it away simply by claiming that what she had examined was data about the sun’s outer surface rather than its interior.

Absent a generally accepted explanation of how hydrogen and helium could produce the sun’s energy, Payne’s findings could not easily override her contemporaries’ preconceptions. We now know that the sun’s heat is generated through nuclear fusion: the sun’s gravitational force compresses together atoms of hydrogen, causing a nuclear reaction. This reaction produces enormous amounts of energy while forming helium and other elements. But this process— so well charted today that even elementary physics textbooks discuss it—was inadequately understood in the 1920s. The emergence of that understanding— which relied on Einstein’s equation governing the relationship between mass and energy—eventually provided strong confirmation of Payne’s results.

“In the early 1900s, most astronomers mistakenly believed”- is a GMAT reading comprehension passage with answers. Candidates must have a solid grasp on English GMAT reading comprehension. There are seven comprehension questions in this GMAT Reading Comprehension section. GMAT Reading Comprehension questions are designed to evaluate candidates' abilities to comprehend, analyze, and apply information or concepts. Candidates can actively prepare by answering GMAT Reading Comprehension Practice Questions.

Solutions and Explanation

1. The passage provides enough information to answer which one of the following questions?

(A) Does the iron content of Earth exceed 50 percent of its total mass?
(B) Who first proved that the sun generates heat from hydrogen by nuclear fusion?
(C) Do any objects in the solar system other than Earth and the sun contain iron?
(D) What percentage of the sun’s mass is composed of iron?
(E) Can the fusion of atoms other than hydrogen atoms produce energy?

2. The passage provides enough information to answer which one of the following questions?

(A) Did Payne at any time believe that the sun was mainly composed of iron?
(B) When Payne first proposed her theory about the sun's composition did any other astronomers fully accept it?
(C) In what year did Payne first receive definitive recognition for her work from other scientists?
(D) Was Payne ever offered an academic appointment?
(E) Did Payne play a significant role in showing the mechanism by which nuclear fusion occurs?.

3. The passage provides the strongest support for believing that some scientists in the 1920s held which one of the following views regarding Payne’s interpretation of the spectroscopic data relating to the sun?

(A) The methodology she used in analyzing the data was outdated, and thus her findings were of doubtful validity.
(B) Her interpretation of the data was remarkably accurate and proved the traditional interpretation of the data to be incorrect.
(C) Her findi romising and warranted serious consideration, but no definitive assessment of them could be made without verification of certain details.
(D) Her interpretation of the data was not entirely ill founded, but the overall conclusions she drew from the data were wrong.
(E) Her interpretation and the overall conclusions she drew from it were correct, but those conclusions were of little scientific consequences.

4. Based on the information in the passage, it can be inferred that the author holds which one of the following views?

(A) The fact that Payne’s research findings were not found convincing by many of her contemporaries was not due to any major mistake in her scientific reasoning.
(B) Previous to Payne, interpreters of the spectroscopic data had deliberately disregarded data that suggested the sun sustained some hydrogen.
(C) The “iron” hypothesis would not have been accepted for so long were it not for the prominence and prestige of Lord Kelvin.
(D) The resistance to her findings that Payne encountered among professional astronomers is uncharacteristic of the way science generally operates.
(E) The discovery of nuclear fusion might have been delayed by several decades if Payne had not determined that the sun consists mainly of hydrogen and helium.

5. It can be inferred from information in the passage that the scientists who tried to explain away Payne’s findings by claiming that she had misconstrued the relevance of her data assumed which one of the following to be true?

(A) It is impossible to generate heat through nuclear fusion.
(B) The inside of the sun is not of the same composition as its outer surface.
(C) The sun contained insufficient hydrogen to have warmed Earth for billions of years.
(D) Payne’s preconceptions about the “iron” hypothesis biased her analysis of spectroscopic
(E) Spatiroscopy will not detect the presence of iron if the iron is in an object as far away from Earth as the sun is.

6. Which one of the following statements about spectroscopy is most strongly supported by information in the passage?

(A) Its use during the 1920s was generally confined to the field of astronomy.
(B) It yielded data about the sun’s composition that Payne initially doubted but ultimately came to accept.
(C) It played a crucial, though often unacknowledged, role in the emergence of our present-day understanding of the process of nuclear fusion.
(D) It was regarded by certain prominent scientists in the 1920s as an unproven tool that produced data of often questionable reliability.
(E) It was a technique advanced enough by the 1920s to detect the presence in the sun of elements that constituted considerably less than 10 percent of its mass.

7. The author’s discussion of nuclear fusion in the last paragraph serves primarily to

(A) illustrate the impact of Payne’s findings on a discipline related to, although distinct from, the one in which she ultimately made her mark
(B) explain in part the reactions of Payne’s fellow scientists to her interpretation of the data that she analyzed
(C) clarify an underlying reason for Payne’s rejection of the “iron" hypothesis
(D) show how ultimately to be modified in light of later scientific developments
(E) demonstrate that Payne’s reliance on incorrect data did not prevent her from reaching a sound hypothesis

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