Shoemaker-Levy 9

The comet Shoemaker-Levy 9 collided spectacularly with Jupiter in 1994, an impact Hubble Space Telescope captured in all its startling glory. The giant planet's gravitational pull ripped the comet apart into fragments, resulting in 21 visible impacts. The largest collision created a fireball that rose about 1,800 miles (3,000 km) above the Jovian cloud tops as well as a giant dark spot more than 7,460 miles (12,000 km) across — about the size of the Earth — and was estimated to have exploded with the force of 6,000 gigatons of TNT. Not only did Hubble's observations heighten public interest in the effects of cosmic impacts, they also shed light on Jupiter's atmosphere.