Comet Shoemaker–Levy 9 brought the impact sites into view for terrestrial observers a few minutes after the collisions. Two other space probes made observations at the time of the impact: the "Ulysses" spacecraft, primarily designed for solar observations, was pointed towards Jupiter from its location away, and the distant "Voyager 2" probe, some from Jupiter and on its way out of the Solar System following its encounter with Neptune in 1989, was programmed to look for radio emission in the 1–390 kHz range and make observations with its ultraviolet spectrometer. The first impact occurred at 20:13 UTC on July 16, 1994, when fragment
Shoemaker (lunar crater) named Mawson (after the Antarctic explorer Douglas Mawson). It was officially named Shoemaker in honor of Eugene Shoemaker, the geologist whose remains were on board the Lunar Prospector spacecraft that impacted this crater floor. This crater became of interest to scientists when the Lunar Prospector detected unusually high concentrations of hydrogen on the floor of this and other nearby craters using a neutron spectrometer. The floor of this crater is kept in permanent shadow from the Sun, and thus maintains a temperature below . Thus the floor forms a cold trap, and any molecules of water that wander into the