Earth travels around the Sun in an elliptical orbit. Because of its elliptical orbit, Earth is not the same distance from the Sun at all times. When Earth is closer to the Sun, the amount of solar power that arrives at Earth's surface is greater. Total solar irradiance, also referred to as solar intensity, is defined as the total solar power received by a unit surface area and is measured in units of watts per square meter. The Sun's power output is 3.86 x 1026 W. The distance from Earth to the Sun is 0.9813 au when Earth is the closest, at perihelion, and 1.0160 au when Earth is the farthest, at aphelion. Calculate the average total solar irradiance Itop at the top of Earth's atmosphere. Express your answer to 4 significant figures. Itop = W/m²