Astronomers also employ other types of measurements, specifically the parsec (pc) . The parsec is defined as the distance to an object with a parallax angle of 1 arcsecond. This takes us back to our measurements using parallax. When determining the relationship between the pc and ly , one finds that:1 pc = 3.261 light years (ly) = 1.9174 x 1012 mi = 3.0857 x 1013 km.M
The parsec was named from the abbreviations of a par allax of one arc sec ond. The idea of the parsec was to provide astronomers a method to calculate stellar and other astronomical distances quickly and with ease from their data. The parsec is preferred by astronomers, whereas the light-year is more popular in science texts and everyday use.