<P> The parsec ( symbol : pc ) is a unit of length used to measure large distances to astronomical objects outside the Solar System . A parsec is defined as the distance at which one astronomical unit subtends an angle of one arcsecond , which corresponds to 7005648000000000000 ♠ 648 000 / π astronomical units . One parsec is equal to about 3.26 light - years ( 30 trillion km or 19 trillion miles ) in length . The nearest star , Proxima Centauri , is about 1.3 parsecs ( 4.2 light - years ) from the Sun . Most of the stars visible to the unaided eye in the night sky are within 500 parsecs of the Sun . </P>
<P> The parsec ( symbol : pc ) is a unit of length used to measure large distances to astronomical objects outside the Solar System . A parsec is defined as the distance at which one astronomical unit subtends an angle of one arcsecond , which corresponds to 7005648000000000000 ♠ 648 000 / π astronomical units . One parsec is equal to about 3.26 light - years ( 30 trillion km or 19 trillion miles ) in length . The nearest star , Proxima Centauri , is about 1.3 parsecs ( 4.2 light - years ) from the Sun . Most of the stars visible to the unaided eye in the night sky are within 500 parsecs of the Sun . </P>
how many astronomical units are in one parsec
how many astronomical units are in one parsec
7005648000000000000 ♠ 648 000 / π
7005648000000000000 ♠ 648 000 / π