Question

Parsec is the unit of:
A) Angle
B) Velocity
C) Time
D) Distance

Answer 1

Hint: One parsec is the distance at which one astronomical unit subtends an angle of one arcsecond. 1 parsec equals 30.8 trillion km. The term parsec is a combination of two words, parallax, and arc second. Parsec is denoted by pc.

Complete solution:
The parsec is defined as a unit of length or distance which is used to measure the large distances to astronomical objects outside the solar system. One parsec is approximately equal to 210,000 astronomical units and equals about 3.3 light-years where the light-year is the distance travelled by the light in a year.
In other words, we can say that parsec is a form of distance corresponding to a parallax of one second.
Parsec, which is the unit for expressing distances to galaxies and stars mostly used by professional astronomers. It indicates the distance at which the radius of the Earth’s orbit is subtending an angle of one second of the arc.
Thus parsec is a unit of distance.

Hence the correct option is D.

Note: 1) The parallax of a star is considered to be half of the angular distance and also stars appear to move relative to the celestial sphere as Earth orbits around the sun.
2) The parsec unit was first suggested by the British astronomer Herbert Hall Turner in 1918.
3) The distances measured in fractions of a parsec usually involve the objects within a solar system.
4) One gigameter is $3.24 \times 10^{-8} pc$. A parsec is greater than a light-year. The parsec is a real scientific measurement.