Question

1 Parsec is approximately equal to

(Where AU is astronomical unit)

• A. 2 × 10⁵ AU
• B. 2 × 10⁶ AU
• C. 2 × 10⁸ AU
• D. 2 × 10¹⁰ AU

Answer 1

Answer: (A)

2 × 10⁵ AU

Answer 2

By definition of parsec

1 parsec $= \frac{IAU}{1arc\sec ond}$

$1{^\circ} = 3600arc\sec ond$

$1{^\circ} = \frac{\pi}{180}rad$

$\therefore$1 arc second $= \frac{\pi}{3600 \times 180}rad$

$\therefore$1 parsec $= \frac{3600 \times 180}{\pi}AU$

$= 206265AU \approx 2 \times 10^{5}AU$