Question

The sun’s angular diameter is measured to be 1920’’. The distance of the sun from the earth is $1.496 \times 10^{11}$m. What is the diameter of the sun?

• A. $1.39 \times 10^{9}m$
• B. $1.39 \times 10^{10}m$
• C. $1.39 \times 10^{11}m$
• D. $1.39 \times 10^{12}m$

Answer 1

Answer: (A)

$1.39 \times 10^{9}m$

Answer 2

Here,

Distance of the sun from the earth, d = $1.496 \times 10^{11}$m Sun’s angular diameter, $\alpha = 1920''$

$\because 1'' = 4.85 \times 10^{- 6}rad$

$\therefore\alpha = 1920'' \times 4.85 \times 10^{- 6}rad$

$= 9.31 \times 10^{- 3}rad$

Sun’s diameter, D = $\alpha d$

$D = (9.31 \times 10^{- 3})(1.496 \times 10^{11})m$

$= 1.39 \times 10^{9}m$