How can I calculate solar intensity at Saturn I'm trying to work out how big solar panels have to be for a Saturn probe, but can't find any data for solar energy at Saturn.
Saturn is about 10.1 AU from Sun, so by the inverse-square law, its solar illumination is a little less than one-hundredth that of Earth, which is also called the solar constant with a value of 1362 W/m².

$$I = I_0 \frac{1\ \mathrm{AU}^2}{R^2} \approx 1362\ \mathrm{W\ m^{-2}}\frac{1^2}{9.583^2}\approx14.83\ \mathrm{W/m^2}$$

Since Saturn's relatively large eccentricity of 0.0565 puts it anywhere between 9.041 and 10.124 AU from the Sun, $I$ varies from 16.66 and 13.29 W/m^2 during its 29.5 year orbital period.