What object crashed into Jupiter in July 1994, leaving scars the size of the planet Earth?

In July of 1994, pieces of the comet Shoemaker-Levy 9 crashed into Jupiter. This was the first observed collision of extraterrestrial objects. The comet had broken apart in 1992 due to tidal forces after being captured and orbiting Jupiter. From July 16 through July 22 of 1994, the pieces of Shoemaker-Levy 9 dramatically slammed into Jupiter at approximately 135,000 Mph, leaving scars in the atmosphere up to 12,500 km across that would remain visible for many months. Gigantic waves from the collision raced across Jupiter at approximately 1,000 miles per hour.

NASA wrote on the following on their blog describing the collision: "This is the first collision of two solar system bodies ever to be observed, and the effects of the comet impacts on Jupiter's atmosphere have been simply spectacular and beyond expectations,"