Light-year Light-year The light-year is a unit of length used to express astronomical distances and measures about 9.46 trillion kilometres or 5.88 trillion miles. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Because it includes the word "year", the term light-year is sometimes misinterpreted as a unit of time. The light-year is most often used when expressing distances to stars and other distances on a galactic scale, especially in nonspecialist and popular science publications. The unit most commonly used in professional astrometry is the parsec
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