The baseball pennant of the Deep Space Niners appears during one of the episodes of Deep Space Nine. The commanding officer of the space station Deep Space Nine is Benjamin Sisko, played by Avery Brooks. In an old college-colleague rivalry Sisko takes up the challenge of playing the logical Vulcans on the virtual Holi-deck, which is basically like a walk in 3D holographic video game.
The pennant of the Niners has a blue blackground with the logo of the team - which is a baseball with a red outline of the space station. Although the space station is not of human design it has been adopted by Captain Sisko. The Niners team is made up of mostly humans but the team also includes a Klingon, Ferengi, Trill and two Bejorans.
Sisko is able to recruit ball players from Deep Space Nine to play baseball against the ruthlessly logical Vulcans.