Why is the sky blue ?

A clear cloudless day-time sky is
blue because molecules in the air
scatter blue light from the sun more
than they scatter red light.  When
we look towards the sun at sunset,
we see red and orange colours
because the blue light has been
scattered out and away from the
line of sight. Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases and particles in the air. Blue light is scattered in all directions by
the tiny molecules of air in Earth's
atmosphere. Blue is scattered more
than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.