A unit of length equal to the distance from the sun to a point having a heliocentric parallax of 1 second.
|1 Parsec (pc)||=||3.08567758x1016m||1 Parsec (pc) (lb)||=||2.062648x105AU (Astronomical Units)|
|1 Parsec (pc)||=||3.2615638 Light Years||1 Parsec (pc) (lb)||=||19.173512x1012 miles|
One parsec is the distance at which a star would appear to shift its position by one arcsecond during the time (about 3 months) in which the Earth moves a distance of one astronomical unit (au) in the direction perpendicular to the direction to the star.
The name parsec is derived from the words parallax second.
See also: Astronomical Unit.