Impact event such as Engelier and Gerin on Iapetus, Mamaldi on Rhea and Odysseus on Tethys and Herschel on Mimas form significant surface features. 2018 models developed to explain the unusual spin of Uranus support a long-held theory that this was caused by an oblique collision with massive object twice the size of Earth. On July 1994, Comet Shoemaker–Levy 9 was a comet that broke apart and collided with Jupiter, providing the first direct observation of an extraterrestrial collision of Solar System objects. The event served as a "wake-up call", and astronomers responded by starting programs such as Lincoln Near-Earth Asteroid Research
4446 Carolyn The "Collaborative Asteroid Lightcurve Link" assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 32.03 kilometers based on an absolute magnitude of 11.2. This minor planet was named by the discoverer after American astronomer Carolyn Shoemaker (born 1929), a prolific discoverer of minor planets and comets, such as Comet Shoemaker–Levy 9. Many of her discoveries were co-discoveries with her husband Gene Shoemaker. The official naming citation was prepared by David Levy and Jean Mueller, and published by the Minor Planet Center on 27 June 1991 (). 4446 Carolyn 4446 Carolyn, provisional designation , is a