A Parsec (9,460,528,405,000 km) is the distance where onesubtends an angle of one arcsecond.
Oneis approximately equal to:
Awas traditionally defined as the distance where one astronomical unit subtends an angle of one arcsecond. A parsec was redefined in 2015 to `648000/?` . Proxima Centauri, is the nearest star to the Sun and is approximately 1.3 parsecs (4.2 light-years) from the Sun.
This unit is often used inwhen more conventional units such as kilometers are too small for easy comprehension, and the is a simple linear transform.