Question

When sunrise and sunset happens ,they appear red. Why?

Answer 1

During sunrise and sunset, the rays have to travel a larger part of the atmosphere because they are very close to the horizon. Therefore, light other than red is mostly scattered away. Most of the red light, which is the least scattered, enters our eyes. Hence, the sun and the sky appear red.

Answer 2

At the time of sunrise and sunset appears red because sun is near the horizon.The rays from the sun have to travel a much larger part of armosphere to reach an observer on earth. So most of blue light is scattered away.The red colour has largest wavelength so it scattered least and it enter our eyes.Hence the sun appears reddish both at the time of sunrise and sunset....
hope it helps..