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
IBM 3270 PC a different System Unit 5371, while their AT counterparts (PC AT/G and PC AT/GX) had System Unit 5373. The additional hardware occupied nearly all the free expansion slots in the computer. It included a video card which occupied 1-3 ISA slots (depending on what level of graphics support was required), and supported CGA and MDA video modes. The display resolution was 720×350, either on the matching 14-inch color monitor (model 5272) or in monochrome on an MDA monitor. A further expansion card intercepted scancodes from the 122-key 3270 keyboard, translating them into XT scancodes which were then sent to the