S06E14 Bart's Comet
Bart alters the school weather balloon and reveals the alteration after the balloon is launched- and Principal Skinner is NOT happy about what it looks like. Skinner is so upset, in fact, that he makes Bart help him with his daily astronomy check- which starts at 4.30am! Bart is mad at himself for altering the balloon... until he makes a discovery- a comet. However Bart finds his fate tied to the "Bart Simpson Comet"- said comet is going to collide with Springfield, destroying Springfield and its inhabitants. A rocket is launched at the comet to destroy it but the rocket soars too high. All it destroys is the bridge that's the only way out of town! Will a miracle beat the comet to Springfield?