Praxis effect

The Praxis effect (also known as the Praxis explosion or Praxis ring) is a special effect sometimes used in science fiction movies and other visual media. The effect is most commonly seen following the explosion of a large object in space — a ring or disc of matter or energy expanding out from the destroyed object. It is named after the explosion of the fictional Klingon moon Praxis at the start of the 1991 science fiction film Star Trek VI: The Undiscovered Country.

The first known use of the effect was in the 1979 science fiction film Alien during the self-destruction of the spaceship Nostromo. It first forms a horizontal multicolored line, with an orange sphere behind or inside it. The shockwave strikes Ellen Ripley's ship a moment later. A similar effect occurs during the evolution of V'Ger in Star Trek: The Motion Picture, released later that same year.

The first acknowledged use of the effect was in the 1991 science fiction film Star Trek VI: The Undiscovered Country. The over-mined Klingon moon of Praxis (after which the effect was named) explodes and throws a ring-like shock wave through space, precipitating the events of the film.

The same visual effect is seen in the background of the cover of the 1992 comic book Supreme #1.

A similar explosion with a horizontal shockwave is seen near the end of the 1994 film Stargate, when Ra's starship is destroyed by a nuclear bomb.

A horizontal shockwave is seen edge-on near the end of the 1996 film Independence Day, when the alien mother-ship is destroyed by a nuclear bomb.

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