InterviewSolution
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InterviewSolution
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why is the sun seen a little before it Rises and for a short while after its sets |
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Answer» This effect is due to the atmospheric refraction of light. At the time of sunrise or sunset, the sun is just near the horizon. The line XY represents the horizon for an observer O on the surface of the earth. Near the surface of earth, air is a little denser than the outer space. The refractive index of the air near the surface of earth is 1.00029 w.r.t. the outer space. Therefore, a ray of light travelling from the sun towards the earth, travels through air, which becomes more and more optically denser. Due to this, it undergoes refraction and therefore gradually deviates towards the normal. As a result, to the observer O on the surface of earth, the sun appears at S'. The apparent shift in the direction of the sun is only 0.5 and the time difference between the actual sunset and the apparent sunset is about 2 minutes. |
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