According to the argument in the text, the Moon's average surface temperature (since it has no atmosphere and is the same distance from the sun as the earth) should also be $255 \mathrm{~K}$, or it would be if all points on its surface had the same temperature (and the Moon has the same average reflectance as the earth). But the Moon rotates very slowly relative to the sun (once a month) and has no atmosphere or ocean to redistribute energy differences. How do you think that these facts might affect the Moon's average temperature? (Hint: Suppose that half the moon was $100 \mathrm{~K}$ hotter and the other was $100 \mathrm{~K}$ colder than the average. Would it still radiate as much energy as it would if its surface area were all at the same temperature?)
A) The average should be less than $255 \mathrm{~K}$.}
B) The average should be more than $255 \mathrm{~K}$.
C) The average should be the same: the energy flowing in must still balance the energy flowing out.

Question

Quizplus · Accepted Answer

The slow rotation and lack of atmosphere mean that the temperature differences across the Moon's surface are extreme, leading to a lower average temperature than if the surface temperature were uniform. This is because the energy radiated by a body increases with the fourth power of its temperature (according to the Stefan-Boltzmann law), so a surface with varying temperatures will radiate less total energy than if the whole surface were at the higher average temperature.

According to the Argument in the Text, the Moon's Average 255 K255 \mathrm{~K}255 K

According to the Argument in the Text, the Moon's Average $255 \mathrm{~K}$