By 1999, astronomers had discovered 17 nearby stars that are orbited

Yes, we OFTEN use the past perfect with a time marker. As described in this post (check out the explanation for choice D), the past perfect tense only makes sense if it describes an action that happened in the distant past, before some other “time marker.” This time marker is often just a later action in simple past tense, but it can also be something like "by 1987."

But do we HAVE to use the past perfect when we see "by + yyyy"? Not necessarily! For a great example of that, check out this post.

If the sentence had been 'By 1999, astronomers had discovered 17 nearby stars that *have been* orbited by planets about the size of Jupiter", would this have been incorrect?

Also, I can't understand how 'are' is justified here since, it refers to only present but this has been happening?

Please help me out.

Thank you!

Hi,

I am not an expert but since I am reviewing this question, I would like to share some of my thoughts.

For your second question, we can use the present tense "are" to state facts or general truths. Even though most GMAT takers might not be astronomers, we should know that the planets do not suddenly stop orbiting, as Earth does not stop orbiting the sun. So, it should be a fact that the 17 stars are orbited by the planets, so we have a good reason to use "are" in the option (A).

For your first question, I do not think it is a good idea to use the perfect present tense to refer the action of orbiting. First, we can just use the present tense for good reasons shown above. Secondly, the use of perfect present tense actually implies that the action has been completed or finished, but the planets do not stop orbiting the 17 stars.

GMATNinja KarishmaB DmitryFarber

Hi, I was confused between option A and C. I understood the error in simple past tense in option C; however, I would like to understand the impact of difference in meaning in option A and C. As per option A, astronomers discovered 17 stars whereas option C means that astronomers discovered the fact that there were 17 stars. Doesn't, the meaning in option C make more sense than meaning in option A? Can this be a reason to reject option A?

waytowharton

While both (A) and (C) might seem to mean the same, option (A) has a more logical meaning and is more direct and clear.

Today morning, he discovered another pathway leading to the river.
Today morning, he discovered that there is another pathway leading to the river.

The two don't necessarily mean the same. In the first sentence, we know that he discovered the path so he was probably walking along and saw a path leading somewhere and followed it and found that it reached the river...
In the second one he has discovered the information that there is another path. Perhaps someone told him? Has he actually found the path, we don't know. Then can we say that he "discovered" that there is another path? Questionable. Perhaps we should say he found out...

What did the astronomers do? They likely discovered the 17 stars. They were looking into their telescopes and found these stars with planets around them. No one told them about it, that is for sure. Also, "they had discovered that there were 17 nearby stars that had planets" seems to mean that there cannot be more than 17. That of all the nearby stars, 17 had planets. We can certainly not be sure of that, right?

Hence, meaning wise, (A) is much clearer and logical. But I had not delved into the meaning till you asked about it. A fact needs present tense and hence we need 'are', not 'were'. That is why I chose (A) directly and did not give (C) a second thought.

My astrology knowledge is little to none. I didn't know up to this point that planets cannot stop orbiting stars out of no where. Do I need to pick up an astrology book before my test day?

Why are we assuming that the given sentence is a FACT. It could also be the case that this fact is no longer valid. Stars and planets DO change positions and orbits. It is very much possible that the orbits of these 17 stars and planets today are not in coherence with the findings of discovery before 1999.
Are we eliminating option C, which is free of any errors, ONLY because it conveys a slightly different MEANING than that conveyed by the original sentence?
So, is it correct to conclude that when there are 2 options, free from errors but with a slight difference in meaning, we should immediately go for option A without thinking too much?

Hello Pankaj0901,

We hope this finds you well.

To answer your query, in this case, the use of the simple present tense is best because the most logical interpretation of the sentence is that at the time of the discovery, at least, the planets did orbit those stars.

Further, it is actually our recommendation that if there are two error-free options that differ in meaning, you select the one that aligns with A, assuming the meaning conveyed by Option A is logical and coherent.

As per our SC approach, the meaning conveyed by Option A should be considered the intended meaning, unless:

1. the meaning conveyed is entirely illogical or incoherent

2. Option A is grammatically incorrect and the only grammatically correct answer choices differ in meaning

We hope this helps.
All the best!
Experts' Global Team

Sometimes, to arrive at the credited answer to an SC question, you have to make a judgment call regarding which choice the writer of the question considered correct.

In this case, (A) is completely logical, and there's no reason not to choose it, whereas the meaning conveyed by the (C) version is a little suspect in that it seems unlikely that what astronomers would have discovered is that, in the past, there were 17 nearby stars that were orbited by planets.

So, while the meaning conveyed by (C) is conceivably logical under certain circumstances, we can get this question correct by going with (A).

For Choice C, I see that an expert notes the following as to why this answer choice is incorrect "Again, this is INCORRECT because the use of past tense here doesn't convey the correct meaning. The discoveries were made in the past, but the planets and stars are still behaving the same way today!" How do we know that these specific stars are still around today though? This SC problem seems to require some sort of background knowledge or to make an inference.

Hello woohoo921,

We hope this finds you well.

To answer your query, you are correct; this question does require a bit of contextual understanding to eliminate C.

However, to some extent this is considered acceptable on GMAT; for example, if a sentence applies the simple present tense to an action taken by Napoleon, we can reasonably be expected to assume that it is incorrect.

Similarly, a statement about a scientific fact or discovery can reasonably be assumed to be a statement of a universal fact, something best conveyed through the simple present tense.

We hope this helps.
All the best!
Experts' Global Team

At best, the timeline in (C) is confusing.

We have a past perfect verb ("had discovered") which points to a time before another moment in the past (1999). Then we get two additional simple past verbs ("were" and "were orbited"). Where do we put those two simple past verbs on the timeline? At 1999? Sometime before the past perfect verb? Did those stars/planets cease to exist well before 1999? Or sometime between 1999 and the present?

The latter, while possible, seems unlikely: did all 17 of those stars suddenly vanish after 1999?. And if we go with the former, that means that the scientists discovered things that no longer exist -- also certainly possible, but seems a little fishy in this context. The reader has to choose between two suspicious (though feasible) options, and that makes the meaning in (C) unclear.

In (A), however, the use of the simple present ("are") makes the meaning clear and unambiguous: the stars are still orbited by the planets, so the reader knows that both still exist.

So (A) is definitely the clearer option, regardless of what you know about astronomy.

The correct answer is (A):

By 1999, astronomers had discovered 17 nearby stars that are orbited by planets.

This sentence uses the correct verb tense (past perfect) to describe an action that was completed before a specified time (1999). Option (B) is also grammatically correct, but it unnecessarily changes the word order and adds a prepositional phrase. Option (C) changes the meaning of the sentence by adding "that there were." Option (D) uses the present perfect tense, which implies a connection to the present, whereas the sentence is describing a past event. Option (E) changes the structure of the sentence and implies that the stars were discovered in 1999, which is not necessarily true.

In OE, It is mentioned that in the second option, " had discovered 17 nearby stars with planets orbiting them that were", 'that' is not clear whether it refers to stars or planets. However, since that is a noun modifier, which is supposed to follow touch rule, isn't it clear that it refers to the planets.

Or is it because of the exception to the touch rule, where 'with planets' is a vital modifier and hence there is ambiguity b/w planets and stars?

daagh GMATNinja egmat Magoosh

It sounds like you've answered your own question!

The touch "rule" is more of a guideline than a rule, as discussed in this post. In choice (B), you could indeed argue that the "that" modifies either "stars" or "planets".

(A) avoids that issue, making it a clearer and better option.

I hope that helps!

Isnt "That" a singular pronoun? why are we using it for 17 nearby stars? I am a bit confused - GMATNinja

"That" can be used as a singular pronoun ("The economy of Chile is stronger than that of Argentina."), but it can also be used as part of a modifier, in which case it can modify both singular and plural nouns.

Check out this post this post for more. This article or this video might help a bit, too.