Question

$1$ parsec = __________ metres

Answer 1

Diameter of Earth’s orbit $=3\times {10}^{11}m$

Radius of Earth’s orbit, $r=1.5\times {10}^{11}m$

Let the distance parallax angle be $1"=4.847\times {10}^{–6}rad$.

Let the distance of the star be D.

Parsec is defined as the distance at which the average radius of the Earth’s orbit subtends an angle of $1"$.

$\theta =\frac{r}{D}$

$D=3.09\times {10}^{16}m$

Hence, $1parsec\approx 3.09\times {10}^{16}m$