The nearly circular orbits of planets in our solar system led scientists to expect that planets around other stars would also reside in circular orbits. However, most known extrasolar planets reside in highly elongated, not circular, orbits. Why? The best clue comes from comets in our solar system. Comets formed in circular orbits but were gravitationally flung into their present-day elliptical orbits when they ventured too close to planets. Astronomers suspect that pairs of planets also engage in this slingshot activity, leaving them in disturbed, elliptical orbits. If two planets form in close orbits, one will be scattered inward (toward its star), the other outward. They will likely then travel close enough to neighboring planets to disturb their orbits also.
The passage suggests that two planets formed in close orbits that engaged in “slingshot activity” would be likely to
- deflect away from each other
- change the shape of each other’s orbit
- affect the orbits of any neighboring planets
An important thing to keep in mind about the Reading Comprehension section of the GRE as we use PowerPrep online to study is that it is just that—reading comprehension. In other words, as difficult as it may seem, and it can be pretty tricky, the test makers will always give us all the information we need in the passage to answer the question. This is still true for questions that ask us about what the passage “suggests,” like question 11 of the second Verbal section on practice test 1.
The question gives us some pretty clear keywords that are highlighted for us in the passage, “slingshot activity.” When this happens, we want to make sure that we DO make sure to narrow our search to the relevant part of the passage, while keeping in mind that that area may be more than just the one sentence in which our keywords appear.
The sentence refers to “this slingshot activity,” which implies that “slingshot activity” was actually defined in the previous sentence. Looking back, we’ll find that the “activity” discussed deals with how comets are flung into elliptical orbits by the gravitational pull of planets that the pass close to. The sentence containing our keywords tells us that it is likely also true that planets have this same relationship that forces them into “disturbed, elliptical orbits.” The following sentence elaborates, telling us that when this happens, one planet is flung “inward,” which is defined as “toward its star,” and the other outward, so the two go in opposite directions. The final sentence tells us that once they are in different orbits, they may pass close to other planets and do something similar.
Ok, so what do we know about “slingshot activity”? Well, apparently it describes the phenomenon in which planets can disturb the orbits of other celestial bodies (comets OR other planets) because of gravity. The result is that one planet is forced closer to its sun and the other farther away, and then there can be a sort of domino effect with other planets. Also, astronomers believe this explains planets’ elliptical orbits.
- deflect away from each other
The passage specified that this “slingshot activity” would cause one planet to “scatter inward” and the other “outward,” which are opposite directions. This does imply, then, that the two planets with “deflect away from each other,” so answer A is supported by information in the passage. We should select this answer.
- change the shape of each other’s orbit
The sentence containing our keywords “slingshot activity” ends in a descriptive -ing phrase that comments on the rest of the sentence “leaving them in disturbed, elliptical orbits.” Since “elliptical” describes the shape of an orbit, and since this is offered as a theory as to why other planets are not in circular orbits, the passage does pretty directly imply that “slingshot activity” is responsible for a “change in the shape of [planets’] orbits.” This answer is supported by the passage and should be selected.
- affect the orbits of any neighboring planets
It’s a bit removed, but the last sentence does mention how “neighboring planets” might be affected after two planets formed close to one another engage in “slingshot activity.” C is also supported by the passage and should be selected.
WOW! All THREE answers are supported by the passage and should be selected. There is NO REASON why this cannot happen on a select-all-that-apply question, so if we find support for all three answers, we should not hesitate to select all three.
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