Self-study
P1
In the early 1900s, most astronomers mistakenly believed that 66 percent of the sun's substance was iron. ███
Old perspective ·
Sun was mostly made of iron
Payne's perspective ·
Sun is mostly hydrogen and helium
Payne's view initially was resisted by astronmers. But eventually it was accepted by them.
P2
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Evidence supporting old perspective ·
Known asteroids contain iron, and spectroscopy
Spectroscopy involves identifying chemical from light patterns. This seemed to show that sun was mostly iron.
Puzzling aspect of old perspective ·
How could something made mostly of iron generate the high energy output of the sun?
Kelvin's answer ·
Sun was contracting, which raised sun's temperature and generated energy
Payne's response ·
Fossil record showed Kelvin's answer was wrong; need to re-examine the iron theory
If sun contracted as Kelvin said, the sun would be much younger than fossil record showed it was. So, iron theory might be wrong and we need to look at the spectroscopic evidence again.
P3
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Payne's interpretation of evidence ·
Spectroscopic data consistent with sun being 90% hydrogen and the rest mostly helium
Although sun has some iron, preconceptions about sun being iron led to prior interpretation that sun was mostly iron.
Astronomers' response ·
Payne was looking only at outer layer of sun
P4
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Confirmation of Payne's perspective ·
Later discovery of nuclear fusion helped confirm Payne was right
During Payne's time, we didn't know how something mostly helium/hydrogen could produce as much energy the sun. Now, we know that the sun's energy is produced by nuclear fusion.
Passage Style
Critique or debate
Phenomenon-hypothesis (RC)
13.
Which one of the following ████ ██████████ █████████ ███ ████ █████ ██ ███ ████████
a
Cecilia Payne was ███ █████ █████████ ██ ████████ ███ █████████ ██ █████ ███ ███ █████████ ███ █████
This isn’t supported, because the passage doesn’t indicate that Payne tried to describe how the sun could produce heat when it was composed of hydrogen and helium. Although she proposed that the sun was composed of hydrogen and helium, we don’t know that she proposed a mechanism by which the sun produces heat. Since (A) isn’t supported, it can’t be the main point.
b
Cecilia Payne proposed ██ ██████████ ███████████ ██ ███ ████ ██ ███ █████ ███████████ ████ █████████ ██ ███ █████ ████ ████████ ███ ████ ███ ██████████ ███████████ █████ ██████████ ████ ████ ██ ██████ ███ ██████
This best captures the overall point of the passage as explained above.
c
Cecilia Payne's use ██ ██████████████ ████ ██ ███████ ███ ████ ██████ █████ ███ ██████████████ ██ ███ █████ ██████████ ███ ████ ██████████ ██ ███ ██████████ ██████████ ███████████ ██████ █████████ █████ ███████
This isn’t supported, because Payne’s use of spectrographic data was not novel and unconventional. It was also used to support the prevailing theory about the sun’s composition. Because (C) isn’t supported, it can’t be the main point.
d
Cecilia Payne was ███ █████ █████████ ██ ███████████ ████ ███ ███ ████████ ████ ████████ ███ ███████ ███ ███ █████ █████████ ███████████ ██████████ ██████████ ██ ███ ██████████ ██████████
This isn’t supported, because Payne didn’t “demonstrate” that the sun contains both hydrogen and helium. She argued that the existing data could be read as indicating that the sun is composed of hydrogen and helium. But this doesn’t constitute a “demonstration” of the sun’s composition. Also, (D) doesn’t capture the widespread acceptance of Payne’s theory.
e
Cecilia Payne was ███ █████ █████████ ██ █████████ ████ ███ █████ ██████ █████ ███ ██ █████████ ██ █████████ █████████ █████ ███████ ██ ███ █████ ███████ ███ ███ ██████ █████ ██████████ ███████ ███████
(E) doesn’t capture the initial resistance to Payne’s theory and its later widespread acceptance. So (E) is too narrow to be the main point.