The many papers by Soviet authors have been translated into English by A. P. Kirillov, N. A. Nikiforova, E. A. Voronov, and others. Some of the papers were trans­ lated by the authors themselves. The discussion records have been prepared at the Institute for Theoretical Astronomy by V. K. Abalakin, N. A. Belyaev, A. P. Kirillov, V. A. Shor, E. A. Voronov, N. S. Yakhontova, and others. The three papers published in French have been carefully checked by B. Milet. The final editing has been done at the Smithsonian Astrophysical Observatory, and we thank J. H. Clark, P. D. Gregory, J. E. Kervick, and G. Warren for retyping much of the material. Our special thanks are due to the D. Reidel Publishing Company for the excellent care they have taken in printing these proceedings of IAU Symposium No. 45. G. A. CHEBOT AREV E. I. KAZIMIRCHAK-POLONSKA Y A B. G. MARSDEN INTRODUCTION The idea to organize a Symposium on 'The Motion, Evolution of Orbits, and Origin of Comets' dates back to the IAU thirteenth General Assembly, held in 1967 in Prague. Owing to the impossibility of completing during the General Assembly the discussion on the problem of orbital evolution of comets Professor G. A. Chebotarev, then the newly elected President of IAU Commission 20, initiated the organization of the international symposium in Leningrad where the full scope of cometary problems might be considered from the viewpoint of celestial mechanics.

Inhalt

1. Evolution of Cometary Orbits on a Cosmogonie Time Scale.- I/Observations and Ephemerides.- 2. Cometary Observations and Variations in Cometary Brightness.- 3. Cometary Brightness Variations and Conditions in Interplanetary Space.- 4. Observations of Comets at the Crimean Astrophysical Observatory.- 5. L'observation des comètes à l'astrographe de l'Observatoire de Nice.- 6. Physical Observations of the Short-Period Comet 1969 IV.- 7. On Establishing an International Service for Cometary Observations and Ephemerides.- 8. General Remarks on Orbit and Ephemeris Computation.- II/General Methods of Orbit Theory.- A. Analytical Methods.- 9. A Series-Solution Method for Cometary Orbits.- 10. On the Application of Hansen's Method of Partial Anomalies to the Calculation of Perturbations in Cometary Motions.- 11. Orbital Characteristics of Comets Passing Through the 1:1 Commensurability with Jupiter.- 12. The Motions of Bodies Close to Commensurabilities with Jupiter (Abstract).- 13. On the Motion of Short-Period Comets in the Neighbourhood of Jupiter.- 14. Secular Perturbations on Periodic Comets.- B. Numerical Methods.- 15. A Numerical Method of Integration by Means of Taylor-Steffensen Series and Its Possible Use in the Study of the Motions of Comets and Minor Planets.- 16. A Library of Standard Programmes for Constructing Numerical Theories for Studying the Motion and Evolution of the Orbits of the Minor Bodies of the Solar System.- 17. The Solution of Problems of Cometary Astronomy on Electronic Computers.- 18. A Method of Integrating the Equations of Motion in Special Coordinates and the Elimination of a Discontinuity in the Theory of the Motion of Periodic Comet Wolf.- 19. The Use of the Electronic Computer for the Urgent Publication of Astronomical Material.- C. Determination of Orbits.- 20. A Numerical Interpretation of the Homogenization of Observational Material for One-Apparition Comets.- 21. The Problem of Elaboration and Classification of Observational Material for One-Apparition Comets.- 22. The Influence of Properties of a Set of Observations on the Weights of Determination of the Orbital Elements of a One-Apparition Comet.- 23. On the Differential Correction of Nearly Parabolic Orbits.- 24. Standardization of the Calculation of Nearly Parabolic Cometary Orbits.- 25. Détermination d'orbites paraboliques à partir de N observations au moyen de l'ordinateur électronique.- III/Motions of the Short-Period Comets.- A. Planetary Perturbations and Nongravitational Effects.- 26. Nongravitational Effects on Comets: the Current Status.- 27. On the Determination of Nongravitational Forces Acting on Comets.- 28. A Search for Encke's Comet in Ancient Chinese Records: A Progress Report.- 29. The Motion of Halley's Comet from 837 to 1910 (Abstract).- 30. A Numerical Analysis of the Motion of Periodic Comet Brooks 2.- 31. Linkage of Seven Apparitions of Periodic Comet Faye 1925-1970 and Investigation of the Orbital Evolution During 1660-2060.- 32. Investigation of the Motion of Periodic Comet Giacobini-Zinner and the Origin of the Draconid Meteor Showers of 1926, 1933 and 1946.- 33. Nongravitational Forces and Periodic Comet Giacobini-Zinner.- 34. A Non-Newtonian Orbit for Periodic Comet Borrelly.- 35. An Investigation of the Motion of Periodic Comet Borrelly from 1904 to 1967.- 36. The Motion of Periodic Comet Pons-Brooks, 1812-1954.- 37. Periodic Comet Tempel-Tuttle and the Leonid Meteor Shower.- 38. Investigation of the Motion of Periodic Comet Stephan-Oterma.- B. Determination of Planetary Masses.- 39. Determination of Planetary Masses from the Motions of Comets.- 40. The Determination of Jupiter's Mass from Large Perturbations on Cometary Orbits in Jupiter's Sphere of Action.- 41. Determination of the Mass of Jupiter from Observations of 10 Hygiea During 1932-1969.- 42. The Motion of Hidalgo and the Mass of Saturn.- 43. On the Determination of Planetary Masses.- 44. The Influence of Minor Planets on the Motions of Comets.- IV/Physical Processes in Comets.- 45. Physical Processes in Cometary Atmospheres.- 46. Some Remarks on the Liberation of Gases from Cometary Nuclei.- 47. The Chemical Composition of Cometary Nuclei.- 48. The Evolution of Cometary Nuclei.- 49. On the Sizes of Cometary Nuclei.- 50. Splitting and Sudden Outbursts of Comets as Indicators of Nongravitational Effects.- 51. On Nongravitational Effects in Two Classes of Models for Cometary Nuclei.- 52. Rotation Effects in the Nongravitational Parameters of Comets.- 53. A Model for the Nucleus of Encke's Comet.- 54. Laboratory Simulation of Icy Cometary Nuclei.- 55. A Nongravita-tional Effect in the Simulation of Cometary Phenomena.- V/Origin and Evolution Of Comets.- A. Orbital Stability and Evolution.- 56. Ejection of Bodies from the Solar System in the Course of the Accumulation of the Giant Planets and the Formation of the Cometary Cloud.- 57. On the Stability of the Oort Cloud.- 58. Determination of the Form of the Oort Cometary Cloud as the Hill Surface in the Galactic Field.- 59. On 'New' Comets and the Size of the Cometary Cloud (Abstract).- 60. Diffusion of Comets from Parabolic into Nearly Parabolic Orbits.- 61. New Estimates of Cometary Disintegration Times and the Implications for Diffusion Theory.- 62. Comets and Problems of Numerical Celestial Mechanics.- 63. The Effect of the Ellipticity of Jupiter's Orbit on the Capture of Comets to Short-Period Orbits.- 64. Evolution of Short-Period Cometary Orbits Due to Close pproaches to Jupiter.- 65. A New Orbital Classification for Periodic Comets.- 66. The Major Planets as Powerful Transformers of Cometary Orbits.- B. Theories of Cometary Origin.- 67. The Origin of Comets.- 68. On the Origin of Comets and Their Importance for the Cosmogony of the Solar System.- 69. The Origin and Evolution of the Comets and Other Small Bodies in the Solar System.- 70. On the Problem of the Origin of Comets.- VI/Relationship with Meteors and Minor Planets.- A. Orbital Evolution of Meteors and Minor Planets.- 71. Investigation of the Orbital Stability of Minor Planets with Cometary Eccentricities.- 72. Evolution of the Orbits of Selected Minor Planets during an Interval of 1000 Years.- 73. Secular Perturbations on the Minor Bodies of the Solar System.- 74. The Use of the Halphen-Goryachev Method in the Study of the Evolution of the Orbits of the Quadrantid and ? Aquarid Meteor Streams.- 75. On the Rate of Ejection of Dust by Long-Period Comets.- 76. Évolution séculaire des orbites de particules météoriques.- 77. Deformatio…