The Sun's luminosity is 3.83 *10²⁶ watts. By the time this energy reaches Earth, it has spread out so that it provides only 1370 watts to each square meter. The orbit of Mars has a mean radius of 1.53 au. How many watts of the Sun's luminosity are provided to each square meter of the surface of Mars? A) 34 B) 153 C) 585 D) 1578

Question

Quizplus · Accepted Answer

The solar constant (the amount of solar energy received per unit area at a distance of one astronomical unit, AU) at Earth is 1370 watts per square meter. Since the intensity of sunlight decreases with the square of the distance from the Sun, at Mars (1.53 AU from the Sun), the intensity is $1370 / (1.53)^2$ watts per square meter. Calculating this gives approximately 585 watts per square meter.

The Sun's Luminosity Is 3