Originally Posted by me in another thread
First of all, you're fighting Sephiroth because he's summoned a meteor to destroy the planet. The meteor is moving probably 2 kilometers per hour but then he can summon this even larger meteor that goes faster than the speed of light (yes, the game does suggest that that it is traveling faster than the speed of light since it takes 8 minutes for light to reach the Earth from the Sun and it gets from the end of our solar system in much less than that)
Why didn't Sephiroth just summon this one to begin with? Anyway, the sun expands far enough to actually touch the Earth and basically engulf your characters and you all get away with scraped knees. This would not only vaporize your party and Sephiroth but the rest of the planet as well.
Next, let's take a look at another interesting plot-hole this move introduces. FINAL FANTASIES DON'T TAKE PLACE ON EARTH! I guess we're all transported to Earth when this move begins or something because we sure weren't there for the rest of the game.
And to top off this "dear-god-please-tell-me-I'm-not-seeing-this" move with a nice big cherry. He can do the damn move multiple times! Destroying already supposedly destroyed planets over again!