QUESTION: Apply the Inverse Square Law to determine the "extraterrestrial solar flux" at the Earth using the Sun's emitted flux = 6.32x10⁷ W/m²based on Wolfram Alpha.

1) Which Inverse Square Law formula should be used?

The formula given in our text (attached below with the Gs) or the formula given on Wolfram Alpha which is

l _ 3.1 6054113" t } To calculate the irradiance drop from a measured value to an unknown value at a known distance, we establish that the irradiance incident from the solar source is G, and note that the surface area of a sphere is calculated by 4 are. The average annual irradiance incident upon Earth (d215million ltmIII is called the solar constant {Gr}, evaluated as 1361 Win12 at the exterior of our atmosphere. The irradiance estimated at the Sun's photosphere is 6.33 x 107 Win11. The Inverse Square law dictates that we scale the irradiance from the surface of the Sun by a factor of ,or 2.155 x 10-5. The irradiance of any additional surface with respect to the Sun [like the average annual irradiance on another planet} is seen in Eq. [32}. By using a method of ratios shown in Eq. [3.2] the proportionality terms cancel out, leaving only the ratio of squared distances (if). 01 _ a? 02 3 (3.2)