Parsec
A unit of distance equal to about 3.26 light-years.
Definition
A parsec (pc) is the distance at which one astronomical unit subtends an angle of one arcsecond. It equals approximately 3.0857 × 10¹⁶ metres, or 3.26156 light-years. The name is a portmanteau of "parallax" and "arcsecond".
Formula
1 pc = 3.085677581 × 10¹⁶ m ≈ 3.26156 ly
Examples
- The nearest star to the Sun, Proxima Centauri, is about 1.295 parsecs away.
- The Milky Way galaxy is roughly 30,000 parsecs (30 kiloparsecs) in diameter.