The Sun has a surface temperature of 5770 K, a radius of 6.96 × 105 km, an average distance from Earth of 1.496 × 108 km, and radiates e/m radiation into space isotropically. Earth is a sphere with a radius of 6378 km, and on average absorbs 30 percent of the sunlight that shines on it, with the rest reflected back into space. Both the Sun and Earth are opaque to e/m radiation of all wavelengths, so intensity I = σT4 , where σ is the Stefan-Boltzmann constant and T is Kelvin temperature. Calculate the temperature (in Kelvins) of Earth.

The Sun has a surface temperature of 5770 K, a radius of 6.96 × 105 km, an average distance from Earth of 1.496 × 108 km, and radiates e/m radiation into space isotropically. Earth is a sphere with a radius of 6378 km, and on average absorbs 30 percent of the sunlight that shines on it, with the rest reflected back into space. Both the Sun and Earth are opaque to e/m radiation of all wavelengths, so intensity I = σT4 , where σ is the Stefan-Boltzmann constant and T is Kelvin temperature. Calculate the temperature (in Kelvins) of Earth.