Astronomy clicker question: hot or not (the cornish hen/turkey effect)

Astronomy 10, Spring Semester 2007
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q5.5

Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the beginning of their learning cycle:

[0.3 points.] Which terrestrial planet has the hottest core?
(A) Mercury, which is closest to the Sun.
(B) Venus, which has the hottest atmosphere.
(C) Earth, which is the most massive.
(D) Mars, which has the tallest volcanos.

Correct answer: (C).

Student responses
Section 4136
(A) : 6 students
(B) : 3 students
(C) : 14 students
(D) : 10 students

Section 5076
(A) : 9 students
(B) : 7 students
(C) : 2 students
(D) : 4 students

The terrestrial planets are subject to the "cornish hen/turkey effect." Suppose a cornish hen and a turkey are both taken out of the oven, where they were at the same temperature. Allowed to cool off on the counter for an hour, the cornish hen (being much smaller) has cooled off considerably, while the interior of the turkey still retains a significant amount of heat. Thus small things cool off faster than larger things. The Earth has a hotter core than any of the other terrestrial planets because it is the most massive, and this results in its current of volcanic and tectonic plate motion activity, compared to the dormant or dead geological activity on the smaller terrestrial planets.

Terrestrial world icosahedra
Originally uploaded by Waifer X.