Why Sky The Blue in Colour?
As the sun light passes through the atmosphere, its rays are scattered by tiny particles of pollen, soot and dust present there. As the blue light is scattered the most, the sky appears blue.
As the time of sunrise and sunset, sunlight has to travel more to teach us. As that time, only red light can be seen because the blue light gets absorbed by the atmosphere.
Below Sky info from Wikipedia (Read More):-
The sky is the part of the atmosphere or of outer space visible from the surface of any astronomical object. It is difficult to define precisely for several reasons. During daylight, the sky of Earth has the appearance of a deep blue surface because of the air's scattering of sunlight.[1][2][3][4] The sky is sometimes defined as the denser gaseous zone of a planet's atmosphere. At night the sky has the appearance of a black surface or region scattered with stars.
During the day the Sun can be seen in the sky, unless covered by clouds. In the night sky (and to some extent during the day) the moon, planets and stars are visible in the sky. Some of the natural phenomena seen in the sky are clouds, rainbows, and aurorae. Lightning and precipitation can also be seen in the sky during storms. On Earth, birds, insects, aircraft, and kites are often considered to fly in the sky. As a result of human activities, smog during the day and light radiance during the night are often seen above large cities (see also light pollution).
http://en.wikipedia.org/wiki/Sky
