In 2006, the International Astronomical Union changed the definition o

Question

In 2006, the International Astronomical Union changed the definition of planet. Controversially, the new definition disqualifies Pluto as a planet. Such a change is not unprecedented. The first asteroids discovered were initially classified as planets. But astronomers soon realized that asteroids are much smaller than the other objects captured by their definition and so numerous that it is impractical to consider them all planets. So planets were redefined to be bodies larger than asteroids.Similarly, astronomers now know that Pluto belongs to a vast population of bodies—several much larger than the largest asteroid—called Kuiper belt objects (KBOs). Eris, a KBO discovered in 2005, is larger than Pluto. If Pluto were a planet, then Eris would also be one, along with many other large KBOs. The number of official planets again threatened to become unwieldy. So, as before, the term planet needed redefinition.

The new definition of planet effectively requires a planet to have more mass than all other bodies in its orbital zone combined (roughly speaking, two bodies share an orbital zone if their orbits cross). Pluto, Eris, and the asteroids do not. But each planet in our solar system has at least 5,000 times the combined mass of the other bodies in its orbital zone. Thus, the definition both restricts the number of planets and captures an important natural division between planets and all other bodies in our solar system.

The new definition of planet effectively requires a planet to have more mass than all other bodies in its orbital zone combined (roughly speaking, two bodies share an orbital zone if their orbits cross). Pluto, Eris, and the asteroids do not. But each planet in our solar system has at least 5,000 times the combined mass of the other bodies in its orbital zone. Thus, the definition both restricts the number of planets and captures an important natural division between planets and all other bodies in our solar system.    1

1. According to the passage, Eris

A. satisfies the International Astronomical Union's new definition of a planet
B. is an asteroid larger than Pluto
C. was classified as a planet when it was first discovered
D. is the largest Kuiper belt object, but smaller than any planet
E. has no more mass than the combined mass of the other bodies in its orbital zone

2 
2. The passage suggests that, of the following, which would be most likely to lead the International Astronomical Union to support a further change to the definition of planet?

A. Many Kuiper belt objects are larger than any asteroid.
B. Each of many dozens of Kuiper belt objects is more massive than all other bodies in its orbital zone combined.
C. No Kuiper belt object qualifies as a planet under the new definition.
D. Several planets orbiting other stars have more than 5,000 times the combined mass of the other bodies in their orbital zones.
E. A new object that is orbiting the sun is discovered and found to have more mass than the combined mass of the other objects in its orbital zone, but not 5,000 times as much.

3 
3. In the context of the passage as a whole, the main function of the first paragraph is to

A. present a historic precedent for the recent change in the definition of planet
B. clarify why the first asteroids discovered were initially classified as planets
C. argue that asteroids should not be classified as planets
D. describe certain details of the new definition of planet
E. explain why Pluto does not qualify as a planet

Vishrut16 · Answer

How is B correct for question 2, there can't be 2 more than 50% in a 100%, if we discover an object greater than mass of all other masses together in its orbit then there cant be a second object satisfying the same....

lalliemoon · Answer

B is correct owing to the fact that the question asks what will prompt a further revision of the new definition. So in light of this, evaluate the statement.

nijat00 · Answer

While I understand why E is correct in Question 1, I don't get why B would be wrong. It is clearly stated in the passage that KBOs are largest asteroids, Eris is a KBO and it is greater than Pluto. Can someone explain it pls?

Vedant_Wankhede · Answer

Yes , You are correct Eris is a   KBO   which is larger than Pluto but the option mentions that Eris is an   asteroid   larger than Pluto.
 We know from the passage that Eris is a KBO but we cannot be sure that is also an asteroid as it can be called as some other object

pearrrrrrr · Answer

1. According to the passage, Eris

A. satisfies the International Astronomical Union's new definition of a planet
B. is an asteroid larger than Pluto
C. was classified as a planet when it was first discovered
D. is the largest Kuiper belt object, but smaller than any planet
E. has no more mass than the combined mass of the other bodies in its orbital zone

The passage states that Eris is a Kuiper Belt Object (KBO) discovered in 2005 and is larger than Pluto. However, it does not meet the new definition of a planet, as it does not have more mass than all other bodies in its orbital zone combined. This characteristic disqualifies Eris from being classified as a planet under the new definition.

Let's evaluate each answer choice:

(A) Incorrect. The passage specifically mentions that Eris does not meet the new definition of a planet.
(B) Incorrect. Eris is described as a Kuiper Belt Object, not an asteroid.
(C) Incorrect. The passage does not mention that Eris was ever classified as a planet.
(D) Incorrect. While Eris is larger than Pluto, there is no indication in the passage that it is the largest KBO or that it is smaller than any planet.
(E) Correct. This aligns with the passage’s description that Eris, like Pluto, does not have more mass than the combined mass of other bodies in its orbital zone, which disqualifies it from being a planet under the new definition.
Answer: (E)

rupayan007 · Answer

Q1 -  "The new definition of planet effectively requires a planet to have more mass than all other bodies in its orbital zone combined (roughly speaking, two bodies share an orbital zone if their orbits cross). Pluto, Eris, and the asteroids do not."

This directly ties with option E.

B would be rejected because, it mentions asteroid larger than Pluto, however, Eris is a KBO, which is larger than the largest asteroid but not necessarily and asteroid itself, as it can be another spatial body.

carcass · Answer

EXPLANATION QUESTION #1

The passage discusses the redefinition of the term "planet" by the International Astronomical Union (IAU) in 2006, which led to Pluto being disqualified as a planet. Here are the key points relevant to the question about Eris:
1. Pluto and Kuiper Belt Objects (KBOs):
- Pluto is part of a vast population of bodies called Kuiper Belt Objects (KBOs).
- Eris, a KBO discovered in 2005, is larger than Pluto.
- If Pluto were considered a planet, then Eris and many other large KBOs would also qualify, making the number of planets "unwieldy."
2. New Definition of a Planet:
- A planet must have more mass than all other bodies in its orbital zone combined.
- Pluto, Eris, and asteroids do not meet this criterion.
- Each planet in our solar system has at least 5,000 times the combined mass of other bodies in its orbital zone.

Question Analysis: According to the passage, Eris...
We need to find the statement that is supported by the passage.
Evaluating Each Option
Option A: satisfies the International Astronomical Union's new definition of a planet
- The passage states that Eris does not meet the new definition (like Pluto, it doesn't have more mass than all other bodies in its orbital zone).
- Incorrect.

Option B: is an asteroid larger than Pluto
- Eris is a Kuiper Belt Object (KBO), not an asteroid. The passage mentions asteroids separately from KBOs.
- Incorrect.

Option C: was classified as a planet when it was first discovered
- The passage doesn't mention Eris's initial classification. It only says Eris's discovery influenced the redefinition.
- Incorrect.

Option D: is the largest Kuiper belt object, but smaller than any planet
- The passage says Eris is larger than Pluto, but it doesn't claim Eris is the largest KBO or compare its size to planets. Also, planets are much more massive, but size isn't directly compared.
- Incorrect.

Option E: has no more mass than the combined mass of the other bodies in its orbital zone
- The passage explicitly states that Pluto, Eris, and asteroids do not meet the new planet definition because they don't have more mass than all other bodies in their orbital zones.
- Correct.

Why Other Options Are Incorrect
- A: Contradicts the passage (Eris doesn't satisfy the new definition).
- B: Misclassifies Eris as an asteroid.
- C: Unsupported (no info on initial classification).
- D: Unsupported (no info on Eris being the largest KBO or size comparison to planets).

Final Answer
E. has no more mass than the combined mass of the other bodies in its orbital zone is the correct choice, as it directly aligns with the passage's description of why Eris isn't a planet under the new definition.

Correct Answer: E

carcass · Answer

EXPLANATION QUESTION #2

The question asks which scenario would most likely lead the International Astronomical Union (IAU) to further change the definition of a planet. To answer this, we need to understand the current definition's rationale and what might prompt a revision.

Key Points from the Passage
1. Current Definition (2006):
- A planet must:
- Orbit the Sun.
- Be spherical (have sufficient mass to assume hydrostatic equilibrium).
- "Clear its orbit" (have more mass than all other bodies in its orbital zone combined).
- Pluto and Eris don't meet the third criterion because they share their orbital zones with many other Kuiper Belt Objects (KBOs).
- Planets in our solar system have at least 5,000 times the combined mass of other bodies in their orbital zones.
2. Reason for the $\mathbf{2 0 0 6}$ Change:
- Without the new definition, many KBOs (like Eris) would qualify as planets, making the number "unwieldy."
- The definition aims to capture a "natural division" between planets and other bodies.

What Would Prompt a Further Change?
A further change would likely occur if the current definition:
- Fails to maintain a practical number of planets (e.g., if too many new objects qualify).
- No longer reflects a "natural division" (e.g., if many objects barely meet the mass dominance criterion).
- Excludes objects that "should" be planets or includes those that "shouldn't" be.

Evaluating Each Option
Option A: Many Kuiper belt objects are larger than any asteroid.
- This was already true before 2006 (Eris is larger than Pluto, which is larger than asteroids). The IAU didn't base the definition on size alone.
- Unlikely to prompt change: Size isn't the issue; orbital dominance is.

Option B: Each of many dozens of Kuiper belt objects is more massive than all other bodies in its orbital zone combined.
- This means dozens of KBOs would qualify as planets under the current definition.
- The 2006 change aimed to avoid an "unwieldy" number of planets. This would directly contradict that goal.
- Most likely to prompt change: The IAU would likely tighten the definition (e.g., raise the mass dominance threshold) to reduce the number.

Option C: No Kuiper belt object qualifies as a planet under the new definition.
- This is already true (Pluto/Eris don't qualify). No pressure to change.
- Unlikely to prompt change.

Option D: Several planets orbiting other stars have more than 5,000 times the combined mass of the other bodies in their orbital zones.
- This aligns with the current definition (our planets meet this threshold). No conflict.
- Unlikely to prompt change.

Option E: A new object is discovered with more mass than others in its orbital zone, but not 5,000 times as much.
- The current definition doesn't require a 5,000:1 ratio; it just notes our planets meet this. The actual requirement is simply "more mass."
- This object would qualify as a planet, but unless many such objects exist, it wouldn't pressure a change.
- Less likely than B to prompt change.

Why Option B is Best
The 2006 change was driven by the impracticality of classifying many KBOs as planets. If many dozens of KBOs suddenly met the mass dominance criterion, the IAU would face the same "unwieldy" problem they tried to solve. They'd likely revise the definition (e.g., requiring a higher mass ratio like 5,000:1) to restore a clear division.

Why Others Are Inferior
- A, C, D: Don't challenge the definition's practicality or natural division.
- E: Only one object wouldn't pressure change; the issue is scale (as in B).

Final Answer
B. Each of many dozens of Kuiper belt objects is more massive than all other bodies in its orbital zone combined is most likely to lead the IAU to further change the definition.

CorrecT Answer is: B

carcass · Answer

EXPLANATION QUESTION #3

The first paragraph states:
1. The IAU changed the definition of "planet" in 2006, disqualifying Pluto.
2. Such changes are not unprecedented (i.e., they've happened before).
3. Historically, the first asteroids discovered were initially classified as planets.
4. Astronomers later redefined planets to exclude asteroids because they were too small and numerous.

Main Function of the First Paragraph
The paragraph does two key things:
- Introduces the $\mathbf{2 0 0 6}$ definition change (Pluto's disqualification).
- Provides historical context (asteroids were once planets but were reclassified) to show that definition changes are not new.

Thus, its main function is to place the 2006 change in a broader historical context by citing a similar past event (asteroid reclassification).

Evaluating the Options
A. Present a historic precedent for the recent change in the definition of planet
- This matches perfectly. The asteroid example is a historic precedent for the Pluto reclassification.
- Strong candidate.
B. Clarify why the first asteroids discovered were initially classified as planets
- The paragraph mentions this, but it's a detail, not the main function.
- Too narrow.
C. Argue that asteroids should not be classified as planets
- The paragraph states this as fact, not as an argument. No persuasive language is used.
- Incorrect focus.
D. Describe certain details of the new definition of planet
- The new definition isn't detailed until the second paragraph.
- Incorrect.
E. Explain why Pluto does not qualify as a planet
- The second paragraph explains this. The first paragraph just mentions Pluto's disqualification without explanation.
- Incorrect.

Why Option A is Correct
The first paragraph's primary role is to contextualize the 2006 change by showing it's not the first time the definition has evolved. The asteroid example is a precedent, making the Pluto change seem less abrupt or controversial.

Why Other Options Are Incorrect
- B, C: Focus on asteroids, which are just an example, not the main point.
- D, E: Address content from the second paragraph, not the first.

Final Answer
A. Present a historic precedent for the recent change in the definition of planet is the main function of the first paragraph.

Correct Answer: A

soham81913 · Answer

To my understanding, the reason why option B   is an asteroid larger than Pluto ] is wrong is because the option is partially incorrect. It is true that Eris is larger than Pluto, but nowhere states that Eris is an asteroid. Eris is a KBO which is larger than largest asteroid.

soumyab12 · Answer

The reason I had rejected B and chosen E here was because of the word "massive". I thought massive means only big by size, and does not mean heavy. Even upon searching the true definition of massive on google, I'm not entirely sure what the definition is...

egmat · Answer

Here's how to approach this systematically:

Step 1: Identify what we're looking for 
The question asks what the passage tells us about Eris specifically. So we need facts that are either directly stated or can be logically deduced from what's written.

Step 2: Locate the information about Eris 
Let me walk you through what the passage actually says about Eris:
 
 Eris is a Kuiper Belt Object (KBO) discovered in 2005 
 Eris is larger than Pluto 
 Most importantly: The passage explicitly states that  "Pluto, Eris, and the asteroids do not"  satisfy the new planet definition

Step 3: Understand what the new definition requires 
Here's the key statement you need to focus on:  "The new definition of planet effectively requires a planet to have more mass than all other bodies in its orbital zone combined."

Now notice what comes right after:  "Pluto, Eris, and the asteroids do not."

Step 4: Make the logical connection 
If Eris does NOT satisfy a definition that requires having "more mass than all other bodies in its orbital zone combined," then what must be true about Eris?

It must have  no more mass  (meaning less than or equal to) the combined mass of other bodies in its orbital zone. That's exactly what answer choice  E  states.

Quick trap to avoid:  Don't pick choice A just because Eris is larger than Pluto. Size and mass dominance in an orbital zone are different things! The passage explicitly groups Eris with objects that fail the new definition.

Also, be careful with choice B - Eris is a KBO, not an asteroid. The passage treats these as distinct categories.

The answer is E.

This question tests your ability to connect explicit statements in the passage and draw straightforward logical conclusions. You can check out the  complete progressive passage analysis on Neuron by e-GMAT  to see how to systematically break down dense RC passages sentence-by-sentence and avoid common trap patterns in detail questions. You'll also find detailed explanations for  hundreds of other official questions on Neuron  with comprehensive frameworks that apply across multiple question types.

Hope this helps! 🎯

allen7011 · Answer

I encountered the same passage but there were three paragraphs with the second starting from "Similarly, astronomers now know that Pluto...." Since one question specifically asks about the function of the first paragraph, it might be more helpful for comprehension of that question if the passage is divided correctly.

AS_23 · Answer

For Q3 - I went with option E. Could you explain how A is correct, especially when the word 'recent' change is also used?

Sajjad1994 · Answer

Hello AS_23

Welcome to GMAT Club!

For this question, you need to recall the main points of the passage.

The first paragraph:

Mentions the 2006 IAU decision that disqualified Pluto as a planet. 
 Says this kind of change is  “not unprecedented.”  
 Gives the example of asteroids, which were first called planets but then reclassified when astronomers realized they were too small and numerous. 
 Implies this historical case is similar to what happened with Pluto and KBOs.

The second paragraph:

Explains the specifics of the new definition and why Pluto fails it.

Now use process of elimination to get to the answer.

(A)  is correct! The asteroid example is clearly used as a historical precedent to show that reclassification has happened before for similar reasons (too many objects, not a natural division).

(E)  is incorrect! It is done more by the second paragraph. The first paragraph sets up the reasoning by analogy.

Answer: A

In 2006, the International Astronomical Union changed the definition o

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GMAT Reading Comprehension (RC) Questions

In 2006, the International Astronomical Union changed the definition o

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615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

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