One Small Step for a Man, One Giant Explosion for Comet Shoemaker-Levy 9

The first chunk of comet Shoemaker-Levy 9's 21 fragments plunged into Jupiter's swirling gaseous soup at 37 miles per second, producing a fireball half as wide as Earth and spurting a plume of gunk 700 miles above the planet's top cloud layer, on July 16, 1994. A quarter century to the day before this 225,000 megaton blast, three men in glittery suits sat atop a 36-story tube filled with tons of flaming propellant and headed for the first walk on...