On the third week of July 1994, comet Shoemaker-Levy crashed into Jupiter's fiery atmosphere. NASA says that another "mystery space object" hit during the same week but 15 years later, leaving a bruise as big as the Pacific Ocean.
Judging by the series of images taken by Hubble's newly installed Wide Field Camera 3, the current theory is that the object was a 488m wide asteroid. Analysis of the angle and size of the bruise reveals that the mystery object possibly came from the Hilda belt, a group of 1100 asteroids orbiting near Jupiter. [NASA via NASA Goddard Twitter]