Interest in close binary stars continues to grow apace. Substantial fractions of the observing time on the International Ultraviolet Explorer and the various X-ray satellites have been devoted to extending our knowledge of a variety of interacting binaries. These, together with applications of novel ground-based techniques and the steady improvement of traditional methods, and developments in methods of analysis, have led to major advances in understanding of the properties and evolution of close binary stars.

Our Symposium Close Binary Stars held in Toronto, 7-10 August 1979, was attended by 170 participants from 26 countries and over 100 papers were presented. The proceedings have been published as IAU Symposium No. 88, Close Binary Stars: Observations and Interpretation, eds. M. Plavec, D.M. Popper and R.K. Ulrich; Reidel Publishing Co., 1980.

The coming of age of space astronomy is evident from the ever increasing involvement of astronomers with space observatories. In the last years we have witnessed a tremendous growth of papers in the literature on the interpretation of results from space observations. The range of astronomical topics affected by space observations is very wide, covering the gammut from stellar birth to cosmology. Chapters following this brief introductions amply illustrate this encouraging development. Space astronomy is no longer a field exploited only by a few specialists.

The years covered in this report (1979-81) have been active ones in the field of stellar classification, as is made obvious in the following sections. In addition to the individual references listed there, a number of symposia, colloquia, and workshops were held during the report period which included papers relevant to stellar classification. These include IAU Symposia 85 (Starclusters), 98 (Be stars), and 99 (Wolf-Rayet stars); IAU Colloquia 64 (Automated Data Retrieval in Astronomy) and 68 (Astrophysical Parameters for Globular Clusters); and the Dudley Observatory Workshop on Problems of Calibration of Multicolor Photometric Systems (1979).

The projects of this Commission are increasingly aimed at the astronomically developing countries. The projects are:

International Schools for Young Astronomers. These are the highest-priority activity of the Commission. They last three weeks, have typically 25 to 35 participants, cover a range of astronomical topics with emphasis on practical training, and are funded by the IAU, UNESCO, and local sources. This report covers three schools: i) La Laguna, Tenerife, Spain, September 1979, participants from Spain, Portugal, Canary Islands and five Latin American countries, ii) Hvar, SR Croatia, Yugoslavia, September – October 1980, participants from Balkan and Mediterranean countries, iii) Helwan Observatory, Cairo, Egypt, participants from Egypt, Saudi Arabia, Sudan, Nigeria, Tanzania, Greece, Portugal, Hungary, China.

For the preparation of this report, I solicited recommendations from all members of the Commission, and also invited them to submit very brief statements of activities of themselves or others that they believed should be considered for inclusion. I received a large number of replies (unfortunately, many in the form of extensive reprints and preprints). I have tried to incorporate most suggestions, and to summarize the activities of Commission members as well as activities described in other sources to provide as broad an account as I have been able of the developments relating to cosmology since the last General Assembly in 1979. In am sure, however, that this report falls short of being complete, especially in the areas of theoretical cosmology, in which I am not really expert.

This commission is intended to study the following problems: (1) the solar corona, i.e. the region of the origin of the solar wind; (2) the heliosphere, i.e. the region dominated by the supersonic solar wind as it expands through the neutral component of the interstellar medium; (3) the heliospheric interface, i.e. the region in which the interaction between the two counterstreaming magnetized plasmas, the subsonic solar wind and the interstellar medium, takes place. The activities of this commission cover both theoretical and observational investigations of these three regions.