Comet Shoemaker–Levy 9 the Cretaceous period is generally thought to have been caused by the Cretaceous–Paleogene impact event, which created the Chicxulub crater, demonstrating that impacts are a serious threat to life on Earth. Astronomers have speculated that without Jupiter to mop up potential impactors, extinction events might have been more frequent on Earth, and complex life might not have been able to develop. This is part of the argument used in the Rare Earth hypothesis. In 2009, it was shown that the presence of a smaller planet at Jupiter's position in the Solar System might increase the impact rate of comets on
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