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
Great January Comet of 1910 twilight, its noticeably curved tail reaching up to 50 degrees by early February. The year 1910 saw considerable media interest in the predicted return of Halley's Comet, which reached perihelion on April 20. The appearance of the Daylight Comet several months earlier therefore came as something of a surprise, and made an extremely strong impression on an expectant public; when Halley's Comet returned again in 1986, many older people's accounts of having seen it in 1910 clearly referred to the Daylight Comet instead. Owing to a "telephonic error", the comet was initially reported as being named Drake's Comet, though once