What is the precise equivalence between one parsec and light-years?
1 parsec is precisely equivalent to about 3.26 light-years
The relationship between the parsec ($ ext{pc}$) and the light-year ($ ext{ly}$) is fixed because both units are derived from fundamental constants related to observation or motion. Since the parsec is derived from the parallax method where $1 ext{ pc}$ corresponds to a star showing an apparent shift of one arcsecond relative to Earth's orbit, its value converts cleanly into light-years. Specifically, one parsec is mathematically established to be equivalent to approximately $3.26$ light-years. This relationship highlights why the parsec is the expertise unit used in professional calculations: it allows astronomers to utilize precise geometric data derived from parallax (which yields arcseconds) directly into a metric unit that bridges to the more commonly understood light-year scale.
