PT128.S4.P3.Q18 > Analytics

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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.

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.

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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.

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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

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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)

18.

Which one of the following ██████████ █████ ████████████ ██ ████ ████████ █████████ ██ ███████████ ██ ███ ████████

Its use during ███ █████ ███ █████████ ████████ ██ ███ █████ ██ ██████████

We have no reason to think spectroscopy was limited to use in astronomy.

It yielded data █████ ███ █████ ███████████ ████ █████ █████████ ███████ ███ ██████████ ████ ██ ███████

We have no reason to think Payne initially doubted the data. She doubted others’ interpretation of the data, but this doesn’t mean she doubted the data.

10%

It played a ████████ ██████ █████ ███████████████ ████ ██ ███ █████████ ██ ███ ███████████ █████████████ ██ ███ ███████ ██ ███████ ███████

We have no reason to think spectroscopy played a role in understanding nuclear fusion.

17%

It was regarded ██ ███████ █████████ ██████████ ██ ███ █████ ██ ██ ████████ ████ ████ ████████ ████ ██ █████ ████████████ ████████████

We have no reason to think that some scientists thought spectroscopy was unreliable.

It was a █████████ ████████ ██████ ██ ███ █████ ██ ██████ ███ ████████ ██ ███ ███ ██ ████████ ████ ███████████ ████████████ ████ ████ ██ ███████ ██ ███ █████

Supported. The analysis could detect that the sun was 10% iron and other elements. It’s reasonable to think at least some of those elements constituted much less than 10% of the sun’s mass, because 10% includes iron and those other elements collectively.

61%

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