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

parsec (pc)

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.

Related category

   • UNITS