Reading Comprehension

PT128 · S4 · P3 · Q13 Cecilia Payne

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In the early 1900s, most astronomers mistakenly believed that 66 percent of the sun's substance was iron.

Topic

How Cecilia Payne discovered the sun is mostly hydrogen and helium — and why her contemporaries resisted her finding.

Framework

Highlight Noteworthy. The author tells the story of Payne's pioneering discovery and the resistance it faced.

Main Point

Cecilia Payne pioneeringly argued the sun is mostly hydrogen and helium (not iron). Her finding was substantiated but resisted because contemporaries had no accepted explanation for how hydrogen and helium could produce the sun's energy. Once nuclear fusion was understood, her result was confirmed.

P1: Payne's claim

Most early-1900s astronomers thought the sun was 66% iron. As a graduate student in the 1920s, Payne argued the sun is mostly hydrogen and helium. Her claim, ultimately accepted, met strong resistance.

P2: Why the iron view held

Earth and asteroids contain iron; spectroscopy seemed to support iron in the sun. But how could iron produce the sun's energy? Lord Kelvin's contraction hypothesis required the sun to be only ~20 million years old — but fossil records suggested billions of years. For Payne, this meant the iron hypothesis (and the spectroscopic evidence behind it) had to be reexamined.

P3: Payne's reanalysis

Payne suspected preconceptions had skewed how the spectroscopic data were read. Analyzed without preconceptions, the data showed 90% hydrogen, most of the rest helium, and some iron and other elements. Most astronomers dismissed her interpretation; some explained it away by claiming she had only examined data about the sun's outer surface, not its interior.

13.

Which one of the following most accurately expresses the main point of the passage?

  1. Cecilia Payne was the first

    Wrong First

    Cecilia argued "pioneeringly" (first paragraph) that the sun is composed largely of hydrogen and helium. She was the first scientist to accurately describe the composition of the sun. Einstein's equation seems more responsible for describing the mechanism (nuclear fusion) by which the sun generates its heat.

    0% picked this

  2. Correct

    Cecilia Payne proposed an innovative

    Why this is right

    This describes the main theme of the passage. It's a little withholding --- like, why are they saying "proposed an innovative alternative" rather than spelling out what that alternative was (mainly H / He, not Iron) -- but everything checks out. The grammar of this answer might also confuse a little bit. The "that prevailed in her time" is meant to modify "view". There was a view of the sun's composition that prevailed in Payne's time, but she proposed an innovative (dare we say "pioneering") alternative. We know that Einstein and introductory textbooks have long since vindicated her view, but we know from the end of the 3rd and beginning of the 4th paragraph that her contemporaries initially bristled at her new idea.

    Skill tested: Main Point · how this choice captures the passage's function is the move to repeat next time.

    66% picked this

  3. Cecilia Payne's use of spectrographic

    Wrong Emphasis Contradicted

    This answer makes it seem like Payne is noteworthy for her tools / methodology, rather than for her theory about the Sun's composition. In fact this answer doesn't even mention the Sun's composition, which was the central part of this whole story. The 1st paragraph is setting the stage for the big picture with sentences about the sun's composition. Moreover, it's actually contradicted that Payne's use of spectrographic data was novel and unconventional, since it was evidence from spectroscopy (2nd sentence of 2nd paragraph) that came up with the old "sun is made of iron" theory in the first place.

    1% picked this

  4. Cecilia Payne was the first

    Wrong First

    This one is cruel. Payne was the first scientist to argue that the sun is composed largely of hydrogen and helium. The previous theory was that 66% of the sun was iron. That doesn't mean that the previous theory (or all scientists before Payne) thought that the sun was 0% hydrogen and 0% helium. In order for her to be the first to think the sun contains hydrogen and helium, all previous scientists would have been thinking the sun has 0 hydrogen atoms, 0 helium atoms, or both. So this answer is taking advantage of anyone who has too loose an understanding of what Payne's discovery was. She didn't discover that there was hydrogen and helium in the sun. She discovered that 90% of the sun is hydrogen and helium, whereas previously it was thought at 34% or less of the sun came from those two elements.

    27% picked this

  5. Cecilia Payne was the first

    Wrong First

    She was the first person to say "the sun is composed largely of hydrogen and helium" (2nd sentence of the passage). We don't know if she was the first to speculate that the sun's energy might not be generated by iron-related processes. Lord Kelvin proposed a continuous-contraction process that would allow the sun to generate energy using iron, but "given the usual assumptions" about the sun, that would mean the sun had only been around for 20 million years. That's presented as an implication most people wouldn't have accepted, so it's likely that many scientists were speculating that we still didn't have a good theory for how the sun generates its energy. But we don't need to prove this answer is contradicted. It's enough to say there's no textual support for the extreme claim that Payne was the first to ever make this speculation.

    6% picked this

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