PrepTest 112, Section 1, Question 13
When astronomers observed the comet Schwassman-Wachmann 3 becoming(65 more words not shown)
Which one of the following,(13 more words not shown)
- AComets often do(15 more words not shown)
- BThe reason comets(17 more words not shown)
- CGas and dust(19 more words not shown)
- DThe amount of(13 more words not shown)
- EThe comet passed(16 more words not shown)
Reading the argument
Why did the comet brighten two months before we could see it breaking into pieces?
My first thought is the time light takes to travel. But wait: the astronomers already saw the increased brightness in September. A general delay in light reaching us doesn't by itself explain why they observed one sign of the breakup before the other. We need to explain the gap between those observations.
What we’re looking for
Maybe breaking apart is a process rather than a single instant. Gas and dust might escape early, producing the brightness, while separate pieces don't become visible until later. That's the kind of explanation I'd look for. The question lets us add information to resolve the apparent conflict, but we must keep both observations and the fact that the astronomers correctly connected the brightness with the breakup.
Working the answers
- A
This puts the emission of gas and dust after the beginning of the breakup. Our puzzle concerns brightness showing up before observers could see separate pieces. Even if the comet began breaking up earlier than September, A doesn't explain why the visible pieces waited until November. It gives a delay before the gas and dust, not an account of the delay between the two observations.
- B
This explains why gas and dust make the comet brighter. We already have that connection. The question is why that brightness can appear before the comet visibly separates into pieces. Naming the light-producing mechanism leaves the timing puzzle in place.
- CCorrect
Cracks can release gas and dust while the comet is still joined together. The early stage of the breakup could therefore produce the September brightness without yet producing separate pieces that the telescopes would reveal.
By November, the comet could have broken all the way through, allowing observers to see the pieces. Both observations now fit one process: gas and dust escape through initial cracks, then the pieces separate later. The brightness was a real sign of the breakup even though the breakup wasn't yet visibly complete. We don't need to claim that gas appears before any crack exists; C specifically gives us cracks that haven't gone all the way through.
- D
A steady increase in gas and dust could explain continuing or increasing brightness. It doesn't explain why gas and dust were visible in September while separate pieces weren't visible until November. We still need the distinction between an early stage that releases material and a later stage of complete separation.
- E
This offers a cause of the breakup. The puzzle isn't what force started it. It is why two observable signs of that breakup appeared at different times. Knowing that the sun's gravitational strain caused the event leaves that two-month gap unexplained.
More Paradox questions
Learn the LSAT our way
Our platform drills Paradox questions at your level and adjusts as you improve.