Question

Why is the actual position of star different from the apparent position?

• A. because star acts as a point source of light
• B. because starlight undergo refraction while entering atmosphere
• C. due to changing refractive index of atmosphere
• D. all of the above

Answer 1

Answer: (A), (B), (C)

The correct options are
A

because star acts as a point source of light

B

because starlight undergo refraction while entering atmosphere

C

due to changing refractive index of atmosphere

Apparent Star Position– It is due to atmospheric refraction of starlight. The temperature and density of the different layer of atmosphere keep varying. Hence we have a different medium. Distant star acts as a point source of light. When the starlight enters the Earth’s atmosphere it undergoes refraction continuously, due to changing refractive index i.e., from rarer to denser. It bends towards the normal. Due to this, the apparent position of the star is different from the actual position.