No. 28: Jul-Aug 1983
Charles Kowal discovered the smooth, very dark sphere called Chiron over five years ago. Only a little more is known about it today. Chiron is 300-400 kilometers in diameter -- asteroid-size. But its orbit (aphelion, 18.9 A.U.; perihelion, 8.5 A.U.) is definitely anomalous for asteroids. One would expect to find only comets in this region of the Solar System. To compound the mystery, Chiron's orbit is unstable. This planetoid was originally somewhere else (no one knows where) and was nudged into its present orbit by a major planet. One group of researchers calculates that Saturn could have been the nudger, and that the event might have happened as recently as 1664!!
(Lipscomb, R.; "Chiron," Astronomy, 11:62, March 1983.)
Comment. Only a minor bit of extrapolation will carry a proponent of catastrophism from a 1664 nudge of a 400-kilometer body to a much more violent Solar System rearrangement sometime during the past 10,000 years.