After urging you all to briefness, I should set a good example. I “welcome you all: participating colleagues and all IAU members and guests, especially those from our host commissions 25, 33 and 45. I thank you all: the contributors to today’s events, to the members of the Organizing Committee, to the Presidents of the sponsoring Commissions, IAU officials and all those who are not here today but have helped to make the arrangements for today’s discussion.

To assist with the direction of our work I have asked Prof. K. Aa Strand, Prof. T. Elvius and Prof. B. Bok to preside over Parts One, Two and Three. Questions and comments may be made to the invited speakers and to the discussion contributors at the end of each Part of our program.