The Praxis effect is a special effect sometimes used in science fiction films 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 .
History
The first known use of the effect was in the 1979 science fiction filmAlien 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 ', released later that same year. The first acknowledged use of the effect was in the 1991 science fiction film '. The over-mined Klingon moon of Praxis 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. The same visual effect appears in the 1993 comedy film Coneheads when Beldar ignites a bottle rocket at a school sporting event. At first, it seems underwhelming, but then there is a large blast with a horizontal ring of energy expanding outward, leaving everyone in shock. A similar explosion with a horizontal shockwave is seen near the end of the 1994 filmStargate, when Ra's starship is destroyed by a nuclear bomb. A horizontal shockwave is seen edge-on near the end of the 1996 filmIndependence Day, when the alien mother-ship is destroyed by a nuclear bomb. Various shots of the shockwave is seen at the end of the first season for the 1996 CG series ,, where Optimus's stasis pod flies towards the hollow moon to destroy it, but is sealed in the pod by Megatron, causing Optimus to be destroyed in a transwarp explosion. The effect is seen twice in the 1997 Special Edition of Star Wars during the explosions of Alderaan and the first Death Star. It is once again seen in the 1997 Special Edition of Return of the Jedi during the explosion of the second Death Star. The 2007 Star Wars Legends novel Death Star explained the ring effect at Alderaan as the shadow of a hyperspace ripple from firing the superlaser at full charge. The effect is also seen near the end of the 1998 filmArmageddon, when the asteroid is split in half by a nuclear bomb. The Praxis effect is also seen in The Return of the King, the third installment of The Lord of the Rings trilogy, when the Eye of Sauron explodes following the destruction of the One Ring.
Physics
Astronomer Philip Plait has described the explosion and resultant shock wave as "the most dramatic effect ever filmed", but states that in reality it would be more likely for the explosion seen in Star Trek VI: The Undiscovered Country to generate a spherical shock wave. He finds the effect to be more plausible when appearing in the Special Edition of during the explosion of the first Death Star, as an explosion traveling from the core of the space station would reach the equatorial trench before the surface of the station and find no resistance at this point. However, the Praxis effect was perpendicular to the trench in this shot, instead of on the same plane. When the second Death Star explodes at the end of the Special Edition of Return of the Jedi, the Praxis effect is on the same plane as the equatorial trench.
