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
Lotus 1-2-3 cartridges but otherwise identical. By early 1984 the software was a killer app for the IBM PC and compatibles, while hurting sales of computers that could not run it. "They're looking for 1-2-3. Boy, are they looking for 1-2-3!" "InfoWorld" wrote. Noting that computer purchasers did not want PC compatibility as much as compatibility with certain PC software, the magazine suggested "let's tell it like it is. Let's not say 'PC compatible,' or even 'MS-DOS compatible.' Instead, let's say '1-2-3 compatible.'" PC clones' advertising did often prominently state that they were compatible with 1-2-3. An Apple II software company promised