19. (a) Give reasons for the following:
(i) The sky appears to be blue during day time to a person on earth.
(ii) The sky near the horizon appears to have a reddish hue at the time of sunset and
sunrise.
(iii) The sky appears dark instead of blue to an astronaut.
(iv) The stars appear to twinkle.
(v) The planets do not twinkle.
CA
Answers
Answer:
A. Because tiny particles are present in light which mainly scatter the blue light and also because the molecules of air and other fine particles in the atmosphere have size smaller than that of the wave length which are more effective in scattering light of shorter wave length. Thus when sunlight passes through the atmosphere the fine particles of air scatter the blue light more strongly than red.
B. The sunlight has to travel larger distance due to which the particles of shorter wavelength scatter away and the light reaches our eyes is of longer wave length i.e red
Explanation:
Answer:
Explanation:
1). The sky appears to be blue during day time to a person on earth. The blue colour of the sky is due to the dominant and preferential scattering of the blue component present in the sunlight by the molecules present in the earth's atmosphere.
2). During sunrise and sunset, the rays have to travel a larger part of the atmosphere because they are very close to the horizon. Therefore, light other than red is mostly scattered away. Most of the red light, which is the least scattered, enters our eyes. Hence, the sun and the sky appear red
3). Scattering of light is the phenomenon that causes the sky to appear blue. Fine dust in the earth's atmosphere scatters the sunlight. ... Thus, there is no question of scattering of light. Thus, the sky appears dark instead of blue to an astronaut.
4). Stars twinkle because … they're so far away from Earth that, even through large telescopes, they appear only as pinpoints. ... As a star's light pierces our atmosphere, each single stream of starlight is refracted – caused to change direction, slightly – by the various temperature and density layers in Earth's atmosphere.
5). The planet are closer to the earth as compared to the stars so the light receive from the planets must greater and the fluctuation caused in the amount of light due to the atmospheric reaction are negligble as a compared to the amount of a light receive from them so that our planets do not twinkle.