Question

a) How many astronomical units (AU) make 1 parsec?
b) Consider the sun like a star at a distance of 2 parsecs. When it is seen through a telescope with 100 magnification, what should be the angular size of the star? Sun appears to be $$(1/2)^0$$ from the earth. Due to atmospheric fluctuations, eye cannot resolve objects smaller than 1 arc minute.
c) Mars has approximately half of the earths diameter. When it is closest to the earth it is at about 1/2 AU from the earth. Calculate at what size it will appear when seen through the same telescope.

Answer 1

(a) According to the definition, 1 parsec is equal to the distance at which 1 AU long arc subtends an angle of 1 s.