Astronomer: In most cases in which a planet has been detected orbiti

Question

Astronomer: In most cases in which a planet has been detected orbiting a distant star, the planet's orbit is distinctly oval, whereas the orbits of Earth and several other planets around our sun are approximately circular. However, many comets orbiting our sun have been thrown into oval orbits by close encounters with planets orbiting our sun. So some of the planets in oval orbits around distant stars were probably thrown into those orbits by close encounters with other planets orbiting the same stars.

Which one of the following, if true, would most strengthen the astronomer's argument?

Which one of the following, if true, would most strengthen the astronomer's argument?

(A)  When two planets or other large objects in orbit have a close encounter, usually the smaller of the two is the more greatly affected.

(B)  There is no indication that the orbit of any planet orbiting our sun has been affected by a close encounter with another planet orbiting our sun.

(C)  In most cases in which planets have been discovered orbiting a distant star, more than one planet has been found orbiting the star.

(D)  Most comets with an oval orbit around our sun were thrown into that orbit by a close encounter with some other object.

(E)  For each distant star that has been found to have a planet, no other object large enough to affect the planet's orbit has been found orbiting the star

LSAT

sandman13 · Answer

(A) When two planets or other large objects in orbit have a close encounter, usually the smaller of the two is the more greatly affected. 
affects them how? maybe vegetation on the planet changes? doesn't affect the conclusion

(B) There is no indication that the orbit of any planet orbiting our sun has been affected by a close encounter with another planet orbiting our sun. 
weakener if anything

(C) In most cases in which planets have been discovered orbiting a distant star, more than one planet has been found orbiting the star. 
so there are other planets around those observed. this might cause the planets to change their path. KEEP

(D) Most comets with an oval orbit around our sun were thrown into that orbit by a close encounter with some other object. 
is that other object a planet? we don't know

(E) For each distant star that has been found to have a planet, no other object large enough to affect the planet's orbit has been found orbiting the star
weakener.

Answer: C

redskull1 · Answer

D is not correct because it is already mentioned in the passage.To strengthen an argument the information should not be present in the argument.It needs to be outside.Am I correct..?

CEdward · Answer

I don't fully understand C. Can someone elaborate?

BenjaminS · Answer

I choose D with the below explanation.
The conclusion is "some of the planets in oval orbits around distant stars were probably thrown into those orbits by close encounters with other planets orbiting the same stars."
To strengthen the conclusion, D says that 
"(D) Most comets with an oval orbit around our sun were thrown into that orbit by a close encounter with some other object."
,so these comets were thrown into that orbit by a close encounter.
This is the same reasoning as the conclusion.

GMATNinja  , Could you please help us?

GMATNinja · Answer

According to the passage, because many  comets  have oval orbits as the result of close encounters with planets orbiting the sun, some  planets  have oval orbits as a result of close encounters with other planets. But how do we know that these planets are comparable to comets? The author seems to assume that the orbits of planets and comets are similar, but he/she provides no basis for doing so.

The question asks for an answer choice that would strengthen the argument. With that in mind, here’s (D):

The passage has already established that MANY comets orbiting the sun are thrown into oval orbits by close encounters with planets. (C) only adds that MOST comets with oval orbits were thrown into oval orbits by a close encounter with some other object.

But we still have no reason to believe that comets and planets are similar. And while we have more information about  comets , we don’t have any additional information about  planets . For that reason, we can eliminate (D).

I hope that helps!

sldisek783 · Answer

Type: Argument
Conclusion: some of the planets in oval orbits around distant stars were probably thrown into those orbits by close encounters with other planets orbiting the same stars
Premise:  many comets orbiting our sun have been thrown into oval orbits by close encounters with planets orbiting our sun
Answer: (C)  In most cases in which planets have been discovered orbiting a distant star, more than one planet has been found orbiting the star.

Why: (C) and (D) are two candidates. (D) is a known fact as it is already mentioned in the argument. In fact, it is the PREMISE!

PK456 · Answer

Could someone please explain why B is wrong

guddo · Answer

Option B weakens the argument instead of strengthening it.

The astronomer uses an analogy: in our solar system, comets get oval orbits from close planetary encounters. To conclude the same could happen to exoplanets, it helps if planetary encounters can indeed alter orbits.

But option B says there’s no sign planets in our solar system have had orbits changed by such encounters. That makes our solar system a poor analogy, if it doesn’t happen here, why assume it happens elsewhere? That undermines the reasoning.

A strengthener should make the analogy more plausible, not less. That’s why B is wrong.

Astronomer: In most cases in which a planet has been detected orbiti

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Astronomer: In most cases in which a planet has been detected orbiti

Prep Toolkit

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