Since sun is faraway from the earth, the sun rays can be assumed parallel when they reach the earth surface.
It takes time 8 min for light to reach from the sun to the earth surface. If speed of light taken to be 3 × 108 ms−1, find the distance from the sun to the earth in km.
when Earth radiates infra red rays, they are radiated back by atmosphere,
so when sun rays come down , are they also radiated back to sun by atmosphere without reaching the earth's ground?