Given that stars and planets initially form from the same gas and dust in space, some astronomers have posited that...
GMAT Information and Ideas : (Ideas) Questions
Given that stars and planets initially form from the same gas and dust in space, some astronomers have posited that host stars (such as the Sun) and their planets (such as those in our solar system) are composed of the same materials, with the planets containing equal or smaller quantities of the materials that make up the host star. This idea is also supported by evidence that rocky planets in our solar system are composed of some of the same materials as the Sun.
Which finding, if true, would most directly weaken the astronomers' claim?
Most stars are made of hydrogen and helium, but when cooled they are revealed to contain small amounts of iron and silicate.
A nearby host star is observed to contain the same proportion of hydrogen and helium as that of the Sun.
Evidence emerges that the amount of iron in some rocky planets is considerably higher than the amount in their host star.
The method for determining the composition of rocky planets is discovered to be less effective when used to analyze other kinds of planets.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Given that stars and planets initially form from the same gas and dust in space, some astronomers have posited that host stars (such as the Sun) and their planets (such as those in our solar system) are composed of the same materials" |
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| "with the planets containing equal or smaller quantities of the materials that make up the host star." |
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| "This idea is also supported by evidence that rocky planets in our solar system are composed of some of the same materials as the Sun." |
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Part B: Provide Passage Architecture & Core Elements
Main Point: Astronomers claim that host stars and their planets are made of the same materials, with planets containing equal or smaller amounts of those materials than their host stars.
Argument Flow: The passage establishes the astronomers' theory based on shared formation origins, specifies that planets should have equal or lesser quantities of stellar materials, and provides supporting evidence from our own solar system's rocky planets.
Step 2: Interpret the Question Precisely
What's being asked? Which finding would most directly weaken the astronomers' claim
What type of answer do we need? Evidence that contradicts or undermines the idea that planets contain equal or smaller quantities of the same materials as their host stars
Any limiting keywords? "most directly" - we need the strongest, most clear-cut contradiction
Step 3: Prethink the Answer
- The astronomers claim planets have the same materials as their host stars, but in equal or smaller quantities
- To weaken this claim most directly, we'd need evidence showing either: Planets contain materials their host stars don't have, OR Planets contain significantly MORE of certain materials than their host stars
- The key word "weaken" means we need contradictory evidence, and "most directly" means it should clearly oppose the central claim rather than just questioning methods or providing tangential information
Most stars are made of hydrogen and helium, but when cooled they are revealed to contain small amounts of iron and silicate.
- This finding about stars containing hydrogen, helium, iron, and silicate when cooled actually supports the astronomers' claim
- It shows stars do contain various materials that could also be found in planets
A nearby host star is observed to contain the same proportion of hydrogen and helium as that of the Sun.
- This shows consistency between different host stars
- Having the same proportion of materials supports the idea of predictable stellar composition
- This evidence would strengthen, not weaken, the astronomers' position
Evidence emerges that the amount of iron in some rocky planets is considerably higher than the amount in their host star.
- This directly contradicts the core claim that planets contain "equal or smaller quantities" of stellar materials
- Finding rocky planets with "considerably higher" iron content than their host star is exactly the opposite of what the theory predicts
- This is the most direct challenge possible
The method for determining the composition of rocky planets is discovered to be less effective when used to analyze other kinds of planets.
- This is about the effectiveness of measurement methods, not about actual compositional findings
- This addresses methodology rather than the substance of the composition claim