Question

Fred Whipple first thought that, like Mercury, Venus keeps one face towards the Sun; if so, the dark side would be very cold. Using Petit and Nicholson’s earlier work he knew this was {not the case, so he concluded Venus must rotate fairly often to keep the dark side warmer. Which of the following is the {original premise} used to reach the conclusion?}

• A. Slow rotation of Venus
• B. Temperature of Venus
• C. Frequent rotation of Venus
• D. Equality of the rate of rotation and revolution

Hint:

Separate {data} (premises) from {inference} (conclusion): if the statement is what the scientist {concluded}, it cannot also be the “original premise”.

Answer 1

The Correct Option is B

To understand the original premise used by Fred Whipple to reach the conclusion about Venus's rotation, we must analyze the thought process. Whipple initially considered that Venus might have one side always facing the Sun, akin to Mercury, resulting in a cold dark side. However, based on prior findings from Petit and Nicholson indicating this was not the case, he determined that Venus had to rotate often enough to keep its dark side warmer. Thus, the key factor leading to the conclusion that Venus must rotate frequently is the observed Temperature of Venus. This observation contradicts the expectation of extreme coldness on the dark side, implying regular rotation to distribute heat. Hence, the correct original premise is the Temperature of Venus, which guided Whipple's reasoning regarding the planet's rotation.