Worlds of David Darling
Encyclopedia of Science
Home > Encyclopedia of Science

parsec (pc)

The parsec (pc) is an astronomical unit of length, equal to the distance at which the radius of the Earth's orbit subtends an angle of one arcsecond. The name is a contraction of "parallax-second."

1 parsec = 3.259 light-years = 206,265 AU = 30.83 trillion km = 19.16 trillion miles.

The parsec is generally used by astronomers in preference to the light-year. For larger distances, the kiloparsec (kpc) = 1,000 pc or megaparsec (Mpc) = 1,000,000 pc are used.

It is a popular misconception that light-year and parsec are units of time. For example, in the Star Wars movie Episode IV: A New Hope, Han Solo says to Obi-Wan: "You've never heard of the Millennium Falcon?... It's the ship that made the Kessel Run in less than twelve parsecs."

12 parsecs, Star Wars

Related category

   • UNITS