Consider a bright star in our night sky. Assume its distance from Earth is 56.1 light-years (ly) and its power output is 4.00 1028 W, about 100 times that of the Sun.
(a) Find the intensity of the starlight at the Earth.
(b) Find the power of the starlight the Earth intercepts. One light-year is the distance traveled by the light through a vacuum in one year. (The radius of Earth is 6.37 106 m.)