LSAT 7 | Section 1 | Logical Reasoning: Q16

LR Question 16 Explanation

QUESTION TEXT: Comets do not give off their own light but reflect light from other …

QUESTION TYPE: Most Strongly Supported

FACTS:

• Comets reflect light from other sources (they don’t emit their own light).
• Scientists estimate comet mass by how bright they appear.
• More mass -> more reflected light -> greater brightness
• A satellite probe found that Halley’s comet reflects 60x less light per unit of mass than previously thought.

ANALYSIS: If the comet reflects less light per unit of mass than previously assumed, but scientists use brightness to estimate mass, then their estimates of the comet’s mass were likely too low.

Why? Because if the comet looks that bright but is much less reflective than expected, then it must be more massive than they thought. In essence:

Same brightness + lower reflectivity = more mass than expected.

___________

1. While this is possible, it’s not supported by the stimulus, which only talks about Halley’s comet.
2. CORRECT. If it reflects much less light per unit mass than previously believed, then earlier estimates based on brightness underestimated its mass.
3. This is a trap. The brightness remained the same. What changed is their understanding of how reflective the material is.
4. The stimulus never compares Halley’s comet to other comets, so we can’t draw conclusions about variation across comets.
5. That might be true, but it goes beyond the scope of the stimulus. The stimulus gives us enough to say previous estimates were too low, not that no estimate can be made at all.