$6.$ The rate at which sunlight reaches the outer edge of the atmosphere of Earth is $1,370$ W$/$m$2($the solar constant for earth$).$ The Earth$$s orbit has an average radius of $150$ x $106$ km$.$ Solar radiation decreases as the square of the distance from the sun. Estimate the solar constant for,

a$.$ Mars, whose orbit has a radius of $228$ x $106($Answer: S $=593$ W$/$m$2)(1/2$ point$)$

b$.$ Venus, whose orbit has a radius of $108$ x $106($Answer: S $=2643$ W$/$m$2)(1/2$ point$)$