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Question
By how much time the day would have been shorter if the earth had no atmosphere?
Solution
Atmospheric refraction causes the sun to appear two minutes before it is actually above the horizon (advanced sunrise). Also, we can see the sun for about two minutes even after it is actually below the horizon (delayed sunset). Therefore, the time from sunrise to sunset is increased by about four minutes because of the refraction of light through the earth's atmosphere. If the earth had no atmosphere, the length of the day would have been shorter by about four minutes.
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RELATED QUESTIONS
What is atmospheric refraction? Use this phenomenon to explain the following natural events:
Twinkling of stars
Draw diagrams to illustrate your answers.
Explain why the planets do not twinkle.
The phenomenon that causes the twinkling of stars is refraction of light.
State whether the following statement is true or false:
The planets twinkle at night due to atmospheric refraction of light.
Fill in the following blank with suitable word:
We can see the sun about ................ minutes before the actual sunrise and about ................ minutes after the actual sunset because of atmospheric ................
What is atmospheric refraction? What causes atmospheric refraction?
We know that light refracts (or bends) when it goes from one medium to another. Now, the atmosphere contains only air. Then how does light get refracted on passing through only air in the atmosphere?
Why does the sky appear blue on a clear day?
Which of the following is not caused by the atmospheric refraction of light?
(a) twinkling of stars at night
(b) sun appearing higher in the sky than it actually is
(c) sun becoming visible two minutes before actual sunrise
(d) sun appearing red at sunset
A star sometimes appears brighter and some other times fainter. What is this effect called? State the reason for this effect.
