Published online by Cambridge University Press: 12 April 2016
The four most prominent returns of the Leonid shoiver in the past decade fall into two broad classes. The 1966 and 1969 showers were of short duration, had a high proportion of small particles, and occurred with the longest apparent delay after the perihelion passage of the parent comet Temple-Tuttle. By contrast, the 1961 and 1965 returns were of long duration, and had more large particles. The 1961 return preceded the comet.
There are three major influences on particle orbits: ejection velocity, radiation pressure, and close encounters with planets. The observations are explainable in a qualitative way on the basis of the first two. But some speculation concerning the results of planetary perturbations must be invoked.
The author has discovered an error in his calculations that modifies the results as presented at the symposium. This paper is a revised version.