Extraterrestrial Radiation

In the previous article, we learnt that the sun generates 3.85×10³⁸ W and in this article, we will learn the portion of power receives at the outer edge of the earth’s atmosphere.

Since the sun is spherical, it emits power in all directions.

Since earth rotates around the sun in an elliptical orbit, distance from earth to the sun always vary from 147.5 million km to 152.1 million km. The average distance from the sun to outer edge of earth’s atmosphere is 149.5 million km. 

Now we know the radial power emission and the distance, and therefore we can calculate power receives at a 1 m² of the outer edge of earth’s atmosphere using the below formula.

Calculated extraterrestrial radiations are given in the below table. 

Distance	Extraterrestrial Radiation
Minimum	1,414 W/m2
Average	1,367 W/m2
Maximum	1,322 W/m2