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
History of measurement systems in Pakistan of Pakistan adopted the International System of Units (SI) Kos is an ancient unit of distance used in South Asia which is about 2.25 miles. Kos may also refer to about 1.8 km (1⅛ mile) or 3.2 km (2 miles). The Mughal Empire used Farsang (Parsang) for distance, which was in principle the distance a horse would walk in an hour, about 3 miles = 12,000 cubits. A Kanal is a unit of area, equivalent to 5445 square feet or one-eighth of an acre. It is mainly used in Punjab province of Pakistan. Under British rule the Marla and Kanal