question 13 

13. A reporter records the following observations of an astronaut from his space ship. 
(a) The length of the day is same as observed on the earth. 
(b) Sky appears black in colour. 
(c) The star appears to twinkle while the plants do not do so as they do on the earth. Justify each statement. 

Dera students,
(a)Earth spins around its own axis approximately every 24 hours (a sidereal day is 23 hours, 56 minutes, 4 second. On an equinox, day and night are of approximately equal duration all over the Earth. They are not exactly equal, however, due to the angular size of the sun and atmospheric refraction.
(b) Due to absence of atmosphere there is no scattering takes place and the sky appears black.
(c) As the planets are more close to Earth than the stars, they are not appearing as point sources of light. The planet covers a small circular area in space, when viewed from Earth. So, even if light from one point in the circular disc is blocked, light from other points reaches our eyes. Therefore, the light from the planets are not completely blocked from our sight and they do not twinkle.
Regards
Vijaya

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school ka hw than puch rhi h 😝
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yhan*
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(b) bcuz there is no atmospherein the outer space that can scatter the sunlight. As the sunlight is not scattered , no scattered light reach d eyes of d astronauts and d sky appears black 2 dem.
(c) As the planets are more close to Earth than the stars, they are not appearing as point sources of light. The planet covers a small circular area in space, when viewed from Earth. So, even if light from one point in the circular disc is blocked, light from other points reaches our eyes. Therefore, the light from the planets are not completely blocked from our sight and they do not twinkle.
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a) i don't know
b)There is no air in space so due to no scattering and the light in space is too faint to activate cones in our eyes therefore we see through rods hence sky appears black in colour.
c)stars twinkle because they are far from earth and it is for the atmosphere to refract these small rays but planets are closer to earth and a group of light , so light from both edges of  planets cancel each other's refraction that's why planets do not twinkle 
 
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