High Quality Content by WIKIPEDIA articles! The Houston Astros are a Major League Baseball franchise based in Houston, Texas. Formed in 1962, they play in the National League Central division. Also known in their early years as Houston Colt .45s (1962–64), pitchers for the Astros have thrown 10 no-hitters in franchise history. A no-hitter is officially recognized by Major League Baseball only "when a pitcher (or pitchers) retires each batter on the opposing team during the entire course of a game, which consists of at least nine innings". No-hitters of less than nine complete innings were previously recognized by the league as official; however, several rule alterations in 1991 changed the rule to its current form. A no-hitter is rare enough that two teams in Major League Baseball have never had a pitcher accomplish the feat. No perfect games, a special subcategory of no-hitter, have been thrown in Astros history. As defined by Major League Baseball, "in a perfect game, no batter reaches any base during the course of the game."