KinexiaLEARN PHYSICS

Parsec (pc)

Quantity: Distance · Category: Non-SI

The parsec is a unit of astronomical distance equal to about 3.26 light-years. It is defined from parallax: the distance at which one astronomical unit subtends one arcsecond. Professional astronomers use it more than the light-year.

Relation to SI

1 pc = 3.085677581×10¹⁶ m ≈ 3.26156 ly

Examples

  • Proxima Centauri is 1.30 parsecs away.
  • The galactic center is about 8,000 parsecs from Earth.
  • Galaxy distances are usually quoted in megaparsecs (Mpc).