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gourikaajith , asked a question
Subject: Science , asked on 12/1/11

1 . Explain briefly the cause of advanced sunrise and delayed sun set?

2 . Why does the sun appear larger in size during sunrise and sunset?

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Gunjan , added an answer, on 13/1/11
891 helpful votes in Science

Sun can be seen about two minutes before actual sunrise because of refraction of sunlight through the atmosphere. When the sun is just below the horizon, sunlight enters the earth's atmosphere obliquely and gets refracted through the different layers of the atmosphere. As a result of this, sunlight gets bent and reaches the eyes of an observer. Following the path of the light rays entering the eyes, the observer sees the sun slightly above its actual position. As a result of this, sun can be seen about two minutes before the actual sunrise

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Ajay T.s. , added an answer, on 13/1/11
1629 helpful votes in Science

Hi Gourika!

1.  The Sun is visible to us two minutes before the sunrise and two minutes after the Sunset, because of the bending of the light due to atmospheric refraction. The light from the Sun got refracted by the atmospheric layers and reaches the observer. This causes the observer to think that the light is coming straight from the Sun.

2.  The Sun appears bigger in the horizon during Sunrise and Sunset is due to an optical illusion. Actually no size change occurs during Sunrise or Sunset. Still the cause of the illusion is not explained properly.


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Sohan Krisna , added an answer, on 13/1/11
2 helpful votes in Science

When the sun is near the horizon and has not crossed the horizon yetsome of its light rays enter the earth's atmosphere and undergo refraction.When the refracted rays are produced backwards the refracted image of the sun is visible 2 minutes before the actual sunrise.The same phenomenon repeats at the time of sunset

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