Saturday 26 July 2014
The sky (or celestial dome) is everything that
lies a certain distance above the surface of the Earth, including
the atmosphere and outer space. In the field of astronomy, the sky is also
called the celestial sphere. During
daylight, the sky appears to be blue because air scatters blue sunlight more
than it scatters red. At night, the sky appears to be a mostly dark
surface or region scattered with stars. During the day, the Sun can be seen in
the sky, unless obscured by clouds. In the night sky (and to some extent during
the day) the moon, planets and stars are visible in the sky. Source
