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)
16.
The author's discussion of nuclear ██████ ██ ███ ████ █████████ ██████ █████████ ██
a
illustrate the impact ██ ███████ ████████ ██ █ ██████████ ███████ ███ ████████ ████████ █████ ███ ███ ██ █████ ███ ██████████ ████ ███ ████
The author doesn’t suggest that Payne’s findings had an impact on nuclear physics.
b
explain in part ███ █████████ ██ ███████ ██████ ██████████ ██ ███ ██████████████ ██ ███ ████ ████ ███ ████████
This best captures the author’s purpose in bringing up nuclear fusion. Scientists during Payne’s time didn’t know about nuclear fusion, which helps explain why they didn’t accept her interpretation.
c
clarify an underlying ██████ ███ ███████ █████████ ██ ███ ██████ ██████████
Nuclear fusion has nothing to do with why Payne didn’t accept the “iron” hypothesis. Payne wasn’t even aware of nuclear fusion at the time she researched the sun.
d
show how Payne's ████████ ████ ██████████ ██ ██ ████████ ██ █████ ██ █████ ██████████ ████████████
The author doesn’t suggest that Payne’s findings were modified. Payne’s findings were the same — she had a certain view about the composition of the sun. What she didn’t know was how the sun could generate heat despite being composed of helium and hydrogen. Nuclear fusion explains the mechanism, but this doesn’t imply Payne’s findings were modified.
e
demonstrate that Payne's ████████ ██ █████████ ████ ███ ███ ███████ ███ ████ ████████ █ █████ ██████████
The author doesn’t suggest that Payne relied on incorrect data. What Payne lacked was a way of explaining how the sun could produce heat; this doesn’t imply that she used any incorrect data.