Free Practice Question
RC · Reading Comprehension
655-705
Short Passage - Science
Reading Passage
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.
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?
Answer Choices
Correct answer marked belowA
Many Kuiper belt objects are larger than any asteroid.
Each of many dozens of Kuiper belt objects is more massive than all other bodies in its orbital zone combined.
Correct
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.
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What it tests
Your ability to understand a passage, its structure, and what the author is really saying. At the 655-705 level, accuracy and speed both matter.
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Answering from memory or outside knowledge instead of strictly from the passage.
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655-705
Type
RC
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