Chapter 23, Problem 17Q

(a)

To determine

The reason that it makes sense that the stars bend toward vertical direction.

Answer to Problem 17Q

Atmospheric refraction of the earth.

Explanation of Solution

Introduction: Refraction of light through the Earth’s atmosphere is called Atmospheric refraction. The earth’s atmosphere is unevenly distributed which means that it is optically thicker at lower level but it is rarer at higher level.

The index of refraction of atmosphere is slightly greater than that of vacuum of space. According to Snell’s law, as light rays from stars enter in atmosphere, they slow down and also bend towards the normal.

So,the refraction of light is the reason for the stars image.

(b)

To determine

The apparent position of stars as viewed from earth.

Answer to Problem 17Q

The reason for certain is vertical reflection of light rays.

Explanation of Solution

Introduction: Refraction of light through the Earth’s atmosphere is called Atmospheric refraction. The earth’s atmosphere is unevenly distributed which means that it is optically thicker at lower level but it is rarer at higher level.

As the light rays come into atmosphere, they bend towards the vertical and after then they reach the human eyes. As eyes “follow” these rays back into the space, image of the stars appears higher as compared to the actual position.