Question

Why is the actual position of a 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 the atmospheric refraction of starlight. The temperature and density of the different layers 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 the 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.