The sky, also known as the celestial dome, commonly refers to everything that lies a certain distance above the surface of Earth, including the atmosphere and the rest of outer space. In the field of astronomy, the sky is also called the celestial sphere. This is an imaginary dome where the sun, stars, planets, and the moon are seen to be traveling. The celestial sphere is divided into regions called constellations. Usually, the term sky is used from the point of view of the Earth's surface. However, the exact meaning of the term can vary; in some cases, the sky is defined as only the denser portions of the atmosphere, for example.
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. 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. 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 pollution during the night are often seen above large cities.
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Famous quotes containing the word sky:
“I had such a wonderful feeling last night, walking beneath the dark sky while cannon boomed on my right and guns on my left ... the feeling that I could change the world only by being there.”
—Viorica Butnariu, Rumanian student at Bucharest University. letter, Dec. 23, 1989, to American friend. Observer (London, Dec. 31, 1989)
“Seas of bright juice suffuse heaven.
The earth by the sky staid with, the daily close of their junction,
The heavd challenge from the east that moment over my head,
The mocking taunt, See then whether you shall be master!”
—Walt Whitman (18191892)
“The sky is silent too,
Hard as granite and as fixed as fate.”
—Philip Larkin (19221986)