PARSEC

A parsec (pc) is a unit of length used in astronomy to express large distances outside the Solar System. It is defined as the distance at which one astronomical unit subtends an angle of one arcsecond. Because of small-angle geometry, this distance is about 3.0857 × 10^16 meters, or roughly 3.26 light-years, and it equals approximately 206,265 astronomical units. The term was coined by Herbert Hall Turner in 1913. A parsec is not an SI unit, but it is commonly used alongside SI units in astronomical contexts.

Parsecs are used to express stellar distances. A distance measured in parsecs is approximately the reciprocal of the observed annual parallax in arcseconds (d ≈ 1/p). Modern astrometry, including space-based missions, provides precise parallax measurements that yield distances in parsecs. Distances to star clusters, brown dwarfs, and nearby galaxies are often given in parsecs or, for larger scales, in kiloparsecs (kpc) or megaparsecs (Mpc).

Parsec also appears as the name of a contemporary technology company and service aimed at game streaming. Parsec the platform provides low-latency streaming of video games and remote play over the internet. The use of the name in this context is unrelated to the astronomical distance unit, though the shared term can lead to confusion in informal discussion.