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?
Explanation
Context: Some astronomers posit that host stars and their planets are composed of the same materials, with planets containing equal or smaller quantities of the star's materials. This is supported by evidence that rocky solar system planets share some materials with the Sun.
Answer: C) Evidence emerges that the amount of iron in some rocky planets is considerably higher than the amount in their host star.
Why? The astronomers' claim is that planets contain equal or smaller quantities of the materials that make up the host star. If some rocky planets have considerably HIGHER amounts of iron than their host star, this directly contradicts the "equal or smaller quantities" part of the claim.
Traps:
- A) "Most stars are made of hydrogen and helium, but when cooled they are revealed to contain many additional elements" → about stars' composition; doesn't challenge the planet-star similarity claim
- B) "A nearby host star is observed to contain the same proportion of hydrogen as our Sun" → about star-to-star composition similarity; doesn't address the star-planet relationship the claim is about
- D) "The method for determining the composition of rocky planets is discovered to be less precise than previously thought" → about methodological precision; suggests measurements may be inaccurate but doesn't directly weaken the claim