162 ANXUAL REPORT SMITHSONIAN INSTITUTION, 1964 



of the structure of Saturn's ringrs. The djmamics of the rings are 

 considered in a rediscussion of Maxwell's Adams Prize Essay on the 

 stability of the rings. Photometry of rings A and B has been used 

 to derive the optical thickness of five representative portions of the 

 rings and the phase variation and albedo of the ring particles. 



The theory of diffuse reflection from scattering layers based on the 

 equations of radiative transfer breaks down for dense dispersions of 

 scattered particles very large relative to the wavelength. Dr. William 

 M. Irvine's recent examinations of the necessary correction to the 

 usual multiple-scattering theory may relate to the situation of Saturn's 

 rings. 



Disturbances to the motion of Neptune previously attributed to the 

 planet Pluto have been reexamined by Dr. Whipple. Other evidence 

 indicates that Pluto is too small to produce the observed effects. Dr. 

 Wliipple has shown that a belt of comets outside the orbit of Neptune 

 can account for the disturbances. 



A long-range project of Mr. Izsak's concerns the utilization of 

 digital computers for the complex algebraic manipulations required 

 by analytical perturbation theories in celestial mechanics. A com- 

 puter program for the analytical development of the planetary dis- 

 turbing function has just been completed.^ With the help of this 

 program the duplication of Leverrier's classical development for 

 Jupiter and Saturn takes about one minute of computing time. 



Meteoritic science. — Many rich clues to the origin and workings of 

 the solar system are provided by meteorites, meteoroids, interplane- 

 tary dust, and the wide range of phenomena related to them. These 

 phenomena must be contained comfortably in any satisfactory picture 

 of the evolution of the solar system. To exploit the diverse informa- 

 tion offered by these bits and fragments of solid matter, the research 

 program of the Observatory is correspondingly broad. 



Fiscal year 1964 was particularly noteworthy for the meteoritic 

 science program, because several important instrumentation complexes 

 were completed. Large-trough antennas were added to all five remain- 

 ing sites of the Radio Meteor Project*; the full 16-station Prairie 

 Meteorite Network ' went into operation ; the simultaneous optical and 

 radar networks for observing artificial meteors from Wallops Island 

 became operational"; and the mass spectrometer for stable-isotope 

 analyses of meteorites was finished.^ Since observational data are the 

 backbone of any scientific program, the availability of these new 

 facilities holds promise of many productive investigations. 



The addition of large-trough antennas to all the sites of the Har- 

 vard-Smithsonian Radio Meteor Project permitted the collection of 

 reliable data on meteors smaller than any we have previously been 



See footnotes, p. 177. 



