Passage - General Questions

[Administrator]

Passage Discussion

Paragraph One:

The initial paragraph of this passage introduces the reader to the late heavy bombardment (LHB) theory, which concerns the formation of the major craters of the Moon. According to this theory, this rigorous bombardment occurred about four billion years ago, and it is likely that these projectiles also struck the Earth, and that no life could have survived on Earth until this bombardment ended.

Paragraph Two:

In this paragraph, we are introduced to various theories that were developed with evidence based on Moon rock, and on the size and distribution of the craters on the Moon. Because of the size of the craters, some astronomers believe that the LHB is the result of the disintegration of an asteroid or comet. According to this theory, the large astronomical body broke apart and spread debris throughout the inner solar system.

A second theory discussed is that LHB is a misnomer, and that such a cataclysmic event is not necessary to explain the available evidence. According to the proponents of this second theory, the evidence on the Moon simply reflects the period concluding billions of years of a continuous, but declining, heavy bombardment throughout the inner solar system. Impacts from the latter part of the bombardment, according to this theory, erased evidence of earlier bombardment.

A third theory holds that the Moon’s evidence supports a defined cataclysmic cratering period which did not extend to the inner solar system, because of its brief duration. Proponents contend that the disintegration occurred solely within the Earth-Moon system, based on the fact that debris from this event would have been swept up quickly.

Paragraph Three:

The final paragraph provides a new piece of evidence to support the theory that the bombardment extended into the inner solar system, in the form of a rock that was apparently knocked from the surface of Mars and eventually arrived on Earth. With an age estimated at four billion years old, and if this rock is from Mars, it would have been knocked from the planet at about the same time that the Moon went through the LHB. This supports the suggestion that at least two inner solar system planetary systems experienced simultaneous bombardment. The author closes this paragraph by pointing out that to fully determine the scope of the late heavy bombardment, many more such rocks will need to be located, and other surface samples from inner solar system planets may need to be obtained.


SUMMARY: This passage introduces the reader to the concept of late heavy bombardment and the debate that surrounds the explanation of lunar rock samples. Three theories about the LHB are discussed, and recent evidence is introduced, and the author emphasizes the need for more samples and further exploration.

The Structure of the passage is as follows:

• Paragraph One: Provides a definition of the late heavy bombardment (LHB), and a brief explanation of the basic principles, and points out that human life would not have been able to exist before the LHB ended.
  
  Paragraph Two: Discusses three major theories which deal with differing perspectives on the LHB.
  
  Paragraph Three: Introduces evidence to support the notion of simultaneous bombardment of systems within the inner solar system, but points out the necessity of further evidence to determine the pervasiveness of the LHB.

[BWM]

A little help on this one? I have a hard time even getting through the passage, and don't have a clue on the questions.
:

[Steve Stein]

That's a tough one, for sure--were you having problems with the topic, the wording used, the structure of the passage? This one could be considered difficult for a number of reasons, and it can be really helpful to note specifically what makes certain passages particularly challenging.

[BWM]

I think the topic and the wording used give me the most trouble, rather than the structure. I'm very unfamiliar with this type of science and a lot of the technical terms used in the passage.

[Steve Stein]

This passage is a great example of a whole lot of scientific and sophisticated-sounding terms used to tell a story that doesn't have to be all that complex. Here's a basic breakdown:

About four billion years ago, the "late heavy bombardment" (LHB) pelted the moon with debris, creating its major craters. This debris should also have been hitting earth at the same time--important because earth life could not have existed until the LHB was over.

Some say the LHB resulted from an asteroid or comet that broke apart, bombarding the inner solar system. Others say that the so-called LHB was just the end of billions of years of similar activity, with the later rounds destroying evidence of earlier activity. A third group believes that the LHB was brief but did not extend throughout the solar system.

A meteorite that was found on Earth appears to have come from the surface of Mars around the same time as the LHB was taking place, suggesting that bombardment included at least planetary systems in the inner solar system. Still, more evidence is needed to figure out just how widespread the LHB actually was.

I hope that's helpful! Hopefully you can see that much of the intellectualized language is basically smoke and mirrors, and you should be able to go back and make sense of that passage, but for a more complete discussion of that passage, the questions, and that entire test, check out our LSAT Deconstructed Volume 51!

[lsatstudent99966]

Hi there,

Does the evidence introduced in the third paragraph support both the first and the second theory?

Thank you!

[Jeff Wren]

Hi lsatstudent,

The evidence in the third paragraph does support the idea that the bombardment occurred throughout the inner solar system (or at least beyond the moon and Earth, as the third theory suggested). Since both the first and second theories agreed that the bombardment occurred throughout the inner solar system, this evidence supports this part of both of their theories. I prefer to characterize the evidence in the third paragraph as consistent with theories one and two, but appears to be evidence against theory three.