Question

What is Solution:
i).Since the stars are very distant they approximate point sized sources of light. As the path of rays of light coming from the star goes on varying slightly, the apparent position of the star fluctuates and the amount of star light entering the eye flickers the star sometimes appears brighter, and at some other time Fainter which is the twinkling effect.
ii). Sun is visible to us about 2min before the actual sunrise, and about 2min after the actual sunset because of atmospheric refraction. By actual sunrise, means the actual crossing of the horizon by the sun.

Answer 1

Answer:hi frnds ;;;I'm giving a simple answer

There are three main points here,,they were as follows

Explanation:

Number 1 :since light from stars undergoes continuous refraction,there fore a star is slightly visible above it's actual position

Number 2:light from stars are deflected due to dust present in atmosphere

Number 3:a point beam of light comes from stars

So sometimes stars appear to be brighter and sometimes fainter

Answer 2

Answer: The twinkling of a star is due to atmospheric refraction of starlight. The starlight, on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth. The atmospheric refraction occurs in a medium of gradually changing refractive index. Since the atmosphere bends starlight towards the normal, the apparent position of the star is slightly different from its actual position. The star appears slightly higher (above) than its actual position when viewed near the horizon. Further, this apparent position of the star is not stationary, but keeps on changing slightly, since the physical conditions of the earth’s atmosphere are not stationary. Since the stars are very distant, they approximate point-sized sources of light. As the path of rays of light coming from the star goes on varying slightly, the apparent position of the star fluctuates and the amount of starlight entering the eye flickers – the star sometimes appears brighter, and at some other time, fainter, which gives the twinkling effect.