Parsec Parsec The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System. A parsec is defined as the distance at which one astronomical unit subtends an angle of one arcsecond, which corresponds to astronomical units. One parsec is equal to about 3.26 light-years (30 trillion km or 19 trillion miles) in length. The nearest star, Proxima Centauri, is about from the Sun. Most of the stars visible to the unaided eye in the night sky are within 500 parsecs of the Sun. The parsec unit was probably first suggested in
26 Aquilae 26 Aquilae 26 Aquilae (abbreviated 26 Aql) is a binary star system in the equatorial constellation of Aquila. "20 Aquilae" is its Flamsteed designation though it also bears the Bayer designation f Aquilae. It has an apparent visual magnitude of 5.00, which means it is faintly visible to the naked eye. As the Earth orbits the Sun, this star system undergoes a parallax shift of 21.15 mas. This means it is located at a distance of approximately from Earth, give or take a 3 light-year margin of error. This is a single-lined spectroscopic binary system, meaning that the presence of