Parsec (pc)

The parsec, abbreviated as pc, is a unit of astronomical length equivalent to approximately 3.0857×10¹⁶ metres, or about 3.26 light-years. Originating from a combination of "parallax" and "second," it historically described the distance at which one astronomical unit subtends an angle of one arcsecond. In 2015, the International Astronomical Union formally redefined the parsec as an exact ratio of 648,000/π astronomical units.